What is the significance of this phrase and why is this particular aspect of creation noted as not existing anymore in the new earth? The best I can tell is that many times throughout scripture the sea is pictured of chaos, raging, needing to be rebuked, symbolically beasts rise out of the sea in Revelation, etc. So maybe it's symbolic of evil being done away with, but it seems that if the old heaven and earth passing away is to be literally taken, then there is no reason to believe that the sea being no more is not literal. But the question then is why no more sea? Since the vast majority of salt water is titled "Sea", does it mean that in the new earth all the water will be fresh water and no longer salt water?
Literal v Figurative
In your 1st analysis, your understanding of "sea" is not literal, which is correct. Rev. 13:1 says,
And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.
Since the Context of this passage is Figurative, we must understand this passage as Figurative(representative of another reality).
We know that no such 'beast' exists in nature, nor would a "Natural Beast" would be created containing the "Name of Blasphemy"-a term which much be understood Figuratively to have any meaning. This is an example of what J.N. Darby calls "doing violence to the text" if we attempt to understand Literally what is meant Figuratively.
Meaning of "Sea"
Furthermore, we are given an understanding of what "sea" is from Rev. 17. Here, the "woman" who we are told in verse 1 is the "Great Whore(Harlot)" described as sitting on "many waters".
And there came one of the seven angels which had the seven vials, and talked with me, saying unto me, Come hither; I will shew unto thee the judgment of the great whore that sitteth upon many waters(Rev. 17:1)
Yet in verse 3 it says,
So he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet coloured beast, full of names of blasphemy, having seven heads and ten horns.
Of course, this is the same "beast" we saw in Rev. 13:1. Yet in verse 15 it says,
And he saith unto me, The waters which thou sawest, where the whore sitteth, are peoples, and multitudes, and nations, and tongues.
So now we understand what "waters/sea" means in this particular context; the 'beast' ascends out of peoples, multitudes, nations, and tongues which are contrary to the Kingdom of God. No particular nation is described, although if we go into the understanding of the beast, particular nations can be identified. If the waters were a separate entity, they would be described as such, but they are the same as the "Beast arising out of the Sea".
"Sea" v "Living Waters"
So now when we turn to Rev. 21:1, it says,
And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
One could make a case for "no more sea" as being "no more salt water", as Rev. 22:1 says,
And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.
Yet even in this passage, "water of Life" means more than "clean water", as healing is obtained from this water, which is the agency of the Holy Spirit,
He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water.(John 7:38)
The "sea" in Rev. 13:1 are those people who make the "beast"/Antichrist their god. The "sea" is no more in Rev. 21:1, because they have been judged and cast into the Lake of Fire,
And the third angel followed them, saying with a loud voice, If any man worship the beast and his image, and receive his mark in his forehead, or in his hand, 10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb: 11 And the smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name.(Rev. 14:9-11)
Therefore the "sea" is identified as those who have the impure water-giving birth to the "beast/Antichrist". The "living waters" are representative of those who receive Christ and are filled with the Holy Spirit.
I think you are on the right track in thinking that this is meant to speak of the permanently peaceful conditions in Revelation 21 and 22.
Another possibility to consider: since the perfect state at the end of Revelation mirrors the primeval state in Genesis in many ways, the absence of a sea may be another way in which the writer is hearkening you back to the time before the Fall, when:
...the LORD God had not caused it to rain on the earth, and there was no man to till the ground; 6 but a mist went up from the earth and watered the whole face of the ground. (Genesis 2:5b-6)
In short, this not only speaks of the elimination of sin and chaos, but of God's ability to effect a complete restoration of the earth to his original intention.
I'm of the opinion that the "sea" that will be no more is the Dead Sea, not the oceans. The Dead Sea is not a feature of the new Jerusalem which descends to the middle east in the promised land:
KJV Rev 21:1 And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea. Rev 21:2 And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband. Rev 21:3 And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God.
The Dead Sea, too salty to sustain life, is a symbol of death. The absence of the Dead Sea in the New Jerusalem and renewed promised land indicate that there will be no more death:
Rev 22:1 And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb. Rev 22:2 In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.
I just came across this exposition from the Expositor's Bible on what is the OT background for John's vision. I added some bolding:
Ezekiel 47:1-48:35 RENEWAL AND ALLOTMENT OF THE LAND IN the first part of the forty-seventh chapter the visionary form of the revelation, which had been interrupted by the important series of communications on which we have been so long engaged, is again resumed. The prophet, once more under the direction of his angelic guide, sees a stream of water issuing from the Temple buildings and flowing eastward into the Dead Sea. Afterwards he receives another series of directions relating to the boundaries of the land and its division among the twelve tribes. With this the vision and the book find their appropriate close. I. The Temple stream, to which Ezekiel’s attention is now for the first time directed, is a symbol of the miraculous transformation which the land of Canaan is to undergo in order to fit it for the habitation of Jehovah’s ransomed people. Anticipations of a renewal of the face of nature are a common feature of Messianic prophecy. They have their roots in the religious interpretation of the possession of the land as the chief token of the Divine blessing on the nation. In the vicissitudes of agricultural or pastoral life the Israelite read the reflection of Jehovah’s attitude towards Himself and His people: fertile seasons and luxuriant harvests were the sign of His favour; drought and famine were the proof that He was offended. Even at the best of times, however, the condition of Palestine left much to be desired from the husbandman’s point of view, especially in the kingdom of Judah. Nature was often stern and unpropitious, the cultivation of the soil was always attended with hardship and uncertainty, large tracts of the country were given over to irreclaimable barrenness. There was always a vision of better things possible, and in the last days the prophets cherished the expectation that that vision would be realised. When all causes of offence are removed from Israel and Jehovah smiles on His people, the land will blossom into supernatural fertility, the ploughman overtaking the reaper, and the treader of grapes him that soweth seed, the mountains dropping new wine and the hills melting. (Amo_9:13) Such idyllic pictures of universal plenty and comfort abound in the writings of the prophets, and are not wanting in the pages of Ezekiel. We have already had one in the description of the blessings of the Messianic kingdom; and we shall see that in this closing vision a complete remodelling of the land is presupposed, rendering it all alike suitable for the habitation of the tribes of Israel. The river of life is the most striking presentation of this general conception of Messianic felicity. It is one of those vivid images from Eastern life which, through the Apocalypse, have passed into the symbolism of Christian eschatology. "And He showed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb. In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruits every month: and the leaves of the tree were for the healing of the nations." (Rev_22:1-2) So writes the seer of Patmos, in words whose music charms the ear even of those to whom running water means much less than it did to a native of thirsty Palestine. But John had read of the mystic river in the pages of his favourite prophet before he saw it in vision. The close resemblance between the two pictures leaves no doubt that the origin of the conception is to be sought in Ezekiel’s vision. The underlying religious truth is the same in both representations, that the presence of God is the source from which the influences flow forth that renew and purify human existence. The tree of life on each bank of the river, which yields its fruit every month and whose leaves are for healing, is a detail transferred directly from Ezekiel’s imagery to fill out the description of the glorious city of God into which the nations of them that are saved are gathered. But with all its idealism, Ezekiel’s conception presents many points of contact with the actual physiography of Palestine; it is less universal and abstract in its significance than that of the Apocalypse. The first thing that might have suggested the idea to the prophet is that the Temple mount had at least one small stream, whose "soft-flowing" waters were already regarded as a symbol of the silent and unobtrusive influence of the Divine presence in Israel. (Isa_8:6) The waters of this stream flowed eastward, but they were too scanty to have any appreciable effect on the fertility of the region through which they passed. Further, to the southeast of Jerusalem, between it and the Dead Sea, stretched the great wilderness of Judah, the most desolate and inhospitable tract in the whole country. There the steep declivity of the limestone range refuses to detain sufficient moisture to nourish the most meagre vegetation, although the few spots where wells are found, as at Engedi, are clothed with almost tropical luxuriance. To reclaim these barren slopes and render them fit for human industry, the Temple waters are sent eastward, making the desert to blossom as the rose. Lastly, there was the Dead Sea itself, in whose bitter waters no living thing can exist, the natural emblem of resistance to the purposes of Him who is the God of life. These different elements of the physical reality were familiar to Ezekiel, and come back to mind as he follows the course of the new Temple river, and observes the wonderful transformation which it is destined to effect. He first sees it breaking forth from the wall of the Temple at the right-hand side of the entrance, and flowing eastward through the courts by the south side of the altar. Then at the outer wall he meets it rushing from the south side of the eastern gate, and still pursuing its easterly course. At a thousand cubits from the sanctuary it is only ankle-deep, but at successive distances of a thousand cubits it reaches to the knees, to the loins, and becomes finally an impassable river. The stream is of course miraculous from source to mouth. Earthly rivers do not thus broaden and deepen as they flow, except by the accession of tributaries, and tributaries are out of the question here. Thus it flows on, with its swelling volume of water, through "the eastern circuit," "down to the Arabah" (the trough of the Jordan and the Dead Sea), and reaching the sea it sweetens its waters so that they teem with fishes of all kinds like those of the Mediterranean. Its uninviting shores become the scene of a busy and thriving industry; fishermen ply their craft from Engedi to Eneglaim, and the food supply of the country is materially increased. The prophet may not have been greatly concerned about this, but one characteristic detail illustrates his careful forethought in matters of practical utility. It is from the Dead Sea that Jerusalem has always obtained its supply of salt. The purification of this lake might have its drawbacks if the production of this indispensable commodity should be interfered with. Salt, besides its culinary uses, played an important part in the Temple ritual, and Ezekiel was not likely to forget it. Hence the strange but eminently practical provision that the shallows and marshes at the south end of the lake shall be exempted from the influence of the healing waters. "They are given for salt." (Eze_47:11).
Expositor's Bible Commentary
And God said, “Let there be a vault between the waters to separate water from water.” So God made the vault and separated the water under the vault from the water above it. And it was so. God called the vault “sky.” And there was evening, and there was morning—the second day. And God said, “Let the water under the sky be gathered to one place, and let dry ground appear.” And it was so. God called the dry ground “land,” and the gathered waters he called “seas.” And God saw that it was good.
So the "seas" is the water left on earth which were gathered up in one place.
And also this seas - unless you see/think these 2 seas are not the same - as revealed in Revelations, are people, and this will be no more.
Are the waters separated from the seas at creation also people?
I am inclined to the literal as the figurative, ie whatever that is real in this world, are merely symbols and signs, to a greater truth, particularly that in the unseen spiritual realm, in the "new" heaven and earth. And so literal though Genesis may be, there is a symbolic significance is the entire act of Creation.
Jesus said, "I am the Light of the World," and he is the Ancient of Old [Micah], the First Born, even as God created Light on Day 1 of creation. And on Day 2 he separated the waters from the waters. And on Day 4 he created the sun, moon and stars, to be symbols of the days of creation, which are essentially symbols in themselves. And so on.
The reason that The New Heavens and Earth will no longer have need of the sea is two fold. Firstly in Rev 22:1 water will be supplied from the very Throne of Jesus Psalm 46:4 mentions this river as well. Rev 21:6 says that He will supply to slake our thirst. The second reason goes back to the ‘Tower of Babel’. At that time people had banded together and made a Tower. Gen 11:4...Then they said, “Come, let us build ourselves a city, with a tower that reaches to the heavens, so that we may make a name for ourselves; otherwise we will be scattered over the face of the whole earth.”... God had from the beginning wanted man to ‘Scatter’ and populate the earth. And the reason is when man is united together evil spreads quicker and easier and what ever man wants to do, that is to be good or evil is concentrated. However, God came down and scattered and confused their plans by making them speak different languages. More about The Tower of Babel is on Website open-heaven.co.uk. To cut this short the sea is there for the same reason. The sea is a barrier to keep the nations apart. If Satan wants to spread evil he needs to unite man so that his purposes can be accomplished. He is not omnipresent, not omniscient and therefore needs to bring men together in order to traffic evil. In the new earth there is no need for this barrier. There is a great deal more to be said about the sea. A wonderful tool against evil and corruption and at the same time it’s saltiness preserves
What does it mean in Revelation 21:1 when it says, “…and the sea was no more.”?
The "sea" was no more, does not refer to the literal sea, the language in the book of Revelation is symbolic, and in this verse "sea" refers to the masses of wicked mankind which are alienated and opposed to God.
Isaiah 57:20 (NRSV) (the word "mankind" inserted in the verse by me)
20 But the wicked ( mankind) are like the tossing sea that cannot keep still; its waters toss up mire and mud.
In Revelation in which Babylon sits are said to be "peoples and multitudes and nations"
Revelation 17:1, 15 (NRSV)
1 "Then one of the seven angels who had the seven bowls came and said to me, “Come, I will show you the judgment of the great whore who is seated on many waters, 15 And he said to me, “The waters that you saw, where the whore is seated, are peoples and multitudes and nations and languages."
The Bible tells us that after Armageddon there will be new heavens and a new earth: "But, in accordance with his promise, we wait for new heavens and a new earth, where righteousness is at home."(2 Peter 3:13.) The former heavens and earth, that is the corrupt and wicked earthly society and governments will be done away with.
Revelation 21:1 (NABRE)
1 Then I saw a new heaven and a new earth. The former heaven and the former earth had passed away, and the sea was no more.
The former heaven and earth, the "sea" that is today's corrupt and wicked turbulent mankind and governments, estranged and opposed to God and under the influence of Satan will be no more.
I do not believe that the seas are always people and nations. In Daniel seven we see an instance of this being true.
I am looking at the fact that nearly always water, lightning and thunder and fire when we read about Yahweh’s presence being discussed in the old testament. My main focus is The appearance and then the disappearance in the book of Revelation.
In the old testament most appearances of Yahweh have storms and lightning and hail and fire are surrounding God's Holy Presence like it's a barrier keeping God's Holiness from destroying this sinful creation. This is seen in verses like--- 10 But the LORD is the true God; He is the living God and the everlasting King. At His wrath the earth quakes, And the nations cannot endure His indignation. 11 Thus you shall say to them, "The gods that did not make the heavens and the earth will perish from the earth and from under the heavens." 12 It is He who made the earth by His power, Who established the world by His wisdom; And by His understanding He has stretched out the heavens. 13 When He utters His voice, there is a tumult of waters in the heavens, And He causes the clouds to ascend from the end of the earth; He makes lightning for the rain, And brings out the wind from His storehouses. Jeremiah 9 NASB. Next we see God’s appearance at Mt Sinai.
18 Now Mount Sinai was all in smoke because the LORD descended upon it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked violently. 19 When the sound of the trumpet grew louder and louder, Moses spoke and God answered him with thunder. 20 The LORD came down on Mount Sinai, to the top of the mountain; and the LORD called Moses to the top of the mountain, and Moses went up. 21 Then the LORD spoke to Moses, "Go down, warn the people, so that they do not break through to the LORD to gaze, and many of them perish. 22 "Also let the priests who come near to the LORD consecrate themselves, or else the LORD will break out against them." 23 Moses said to the LORD, "The people cannot come up to Mount Sinai, for You warned us, saying, 'Set bounds about the mountain and consecrate it.'" 24 Then the LORD said to him, "Go down and come up again, you and Aaron with you; but do not let the priests and the people break through to come up to the LORD, or He will break forth upon them." 25 So Moses went down to the people and told them. Exodus 19.
Here the sinful Israelites react to God descending Mt. Sinai. In fact next chapter of Exodus says 18 All the people perceived the thunder and the lightning flashes and the sound of the trumpet and the mountain smoking; and when the people saw it, they trembled and stood at a distance. 19 Then they said to Moses, "Speak to us yourself and we will listen; but let not God speak to us, or we will die." 20 Moses said to the people, "Do not be afraid; for God has come in order to test you, and in order that the fear of Him may remain with you, so that you may not sin." 21 So the people stood at a distance, while Moses approached the thick cloud where God was. 22 Then the LORD said to Moses, "Thus you shall say to the sons of Israel, 'You yourselves have seen that I have spoken to you from heaven. 23 'You shall not make other gods besides Me; gods of silver or gods of gold, you shall not make for yourselves. 24 'You shall make an altar of earth for Me, and you shall sacrifice on it your burnt offerings and your peace offerings, your sheep and your oxen; in every place where I cause My name to be remembered, I will come to you and bless you. Exodus 20. These storms are seen in Nahum 1:2-3 as the clouds as the dust of God's feet.
2 A jealous and avenging God is the LORD; The LORD is avenging and wrathful. The LORD takes vengeance on His adversaries, And He reserves wrath for His enemies.
3 The LORD is slow to anger and great in power, And the LORD will by no means leave the guilty unpunished. In whirlwind and storm is His way, And clouds are the dust beneath His feet.
Now getting to the book of Revelation we find as sea of glass underneath God's presence. this is seen also in Ezekiel 1 4 "As I looked, behold, a storm wind was coming from the north, a great cloud with fire flashing forth continually and a bright light around it, and in its midst something like glowing metal in the midst of the fire." in Revelation chapter 4 we see:
1 After these things I looked, and behold, a door standing open in heaven, and the first voice which I had heard, like the sound of a trumpet speaking with me, said, "Come up here, and I will show you what must take place after these things." 2 Immediately I was in the Spirit; and behold, a throne was standing in heaven, and One sitting on the throne. 3 And He who was sitting was like a jasper stone and a sardius in appearance; and there was a rainbow around the throne, like an emerald in appearance. 4 Around the throne were twenty-four thrones; and upon the thrones I saw twenty-four elders sitting, clothed in white garments, and golden crowns on their heads. Next we see the Throne and worship of the Creator in chapter 15. 5 Out from the throne come flashes of lightning and sounds and peals of thunder. And there were seven lamps of fire burning before the throne, which are the seven Spirits of God; 6 and before the throne there was something like a sea of glass, like crystal; and in the center and around the throne, four living creatures full of eyes in front and behind. 7 The first creature was like a lion, and the second creature like a calf, and the third creature had a face like that of a man, and the fourth creature was like a flying eagle. 8 And the four living creatures, each one of them having six wings, are full of eyes around and within; and day and night they do not cease to say, "Holy, holy, holy is the Lord God, the Almighty, who was and who is and who is to come." 9 And when the living creatures give glory and honor and thanks to Him who sits on the throne, to Him who lives forever and ever, 10 the twenty-four elders will fall down before Him who sits on the throne, and will worship Him who lives forever and ever, and will cast their crowns before the throne, saying, 11 "Worthy are You, our Lord and our God, to receive glory and honor and power; for You created all things, and because of Your will they existed, and were created." In Rev 15 we read: 1 Then I saw another sign in heaven, great and marvelous, seven angels who had seven plagues, which are the last, because in them the wrath of God is finished. 2 And I saw something like a sea of glass mixed with fire, and those who had been victorious over the beast and his image and the number of his name, standing on the sea of glass, holding harps of God. 3 And they *sang the song of Moses, the bond-servant of God, and the song of the Lamb, saying, "Great and marvelous are Your works, O Lord God, the Almighty; Righteous and true are Your ways, King of the nations! 4 "Who will not fear, O Lord, and glorify Your name? For You alone are holy; For all the nations will come and worship before You, For Your righteous acts have been revealed." 5 After these things I looked, and the temple of the tabernacle of testimony in heaven was opened, 6 and the seven angels who had the seven plagues came out of the temple, clothed in linen, clean and bright, and girded around their chests with golden sashes. 7 Then one of the four living creatures gave to the seven angels seven golden bowls full of the wrath of God, who lives forever and ever. 8 And the temple was filled with smoke from the glory of God and from His power; and no one was able to enter the temple until the seven plagues of the seven angels were finished. This sea is almost always present as storm cloud or as a sea of glass mixed with fire. In these places God is present as a judge. But Yahweh's presence in the new heaven and new earth the sea is gone. Could this be because sin is finally gone in the new world? I think it might be so.