Does the Bible say much about the ocean? Will it exist in the future?
Symbol of Death
To the Jews, and ancient Israel, the ocean was always a symbol of death. We see that in the language of the sea giving up her dead in the Book of Revelation (Rev 20:13). Interestingly, the word “ocean” appears more in the Book of Revelation  than in nearly all of the rest of the books in the New Testament, and as you can imagine, the language is not about a nice little cruse in the ocean. In the seventh seal, the Apostle John writes, “The second angel blew his trumpet, and something like a great mountain, burning with fire, was thrown into the sea, and a third of the sea became blood” (Rev 8:8), and then, “A third of the living creatures in the sea died, and a third of the ships were destroyed” (Rev 8:9). Later John writes where he “saw a beast rising out of the sea, with ten horns and seven heads, with ten diadems on its horns and blasphemous names on its heads” (Rev 13:1), and a beast that rises out of the sea, would be bad news for a people who are not seafaring people, which the Jews are.
Not a Seafaring People
As I wrote earlier, the Jews were not a seafaring people. In Solomon’s day, they were for a time, but they were no match for the Phoenicians and the Egyptians, who often battled for control of the Mediterranean Sea, so to the Jews, the sea was not a safe place to be, at least in ancient times. The sea is vividly displayed as a symbol of death in the Book of Revelation when “a mighty angel took up a stone like a great millstone and threw it into the sea, saying, “So will Babylon the great city be thrown down with violence, and will be found no more” (Rev 18:21). Jesus once symbolized death by the use of the ocean where He said in regards to causing someone to stumble, “It would be better for him if a millstone were hung around his neck and he were cast into the sea than that he should cause one of these little ones to sin” (Luke 17:2). Here, the ocean is seen as a form of judgment, and one that lasts forever, very much like death.
New Heaven and New Earth
The Apostle John surely didn’t understand everything he saw in his visions recorded in the Book of Revelation, but the vision of the New Jerusalem coming out of heaven must have been overwhelming. He writes where he “saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and the sea was no more” (Rev 21:1), so there is a new heaven and a new earth, and these new heaven and new earth will have no more death, sorrow, pain, or suffering in them. John writes that God “will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away” (Rev 21:4). Then Jesus declares, “Behold, I am making all things new” (Rev 21:5), including the fact that “the sea was no more” (Rev 21:1). With the sea being declared “no more,” there comes a new heaven and a new earth, and no more sea is in it. Perhaps what is being symbolized is there will be no more death, and the sea which often depicted death, is now “no more.”
The Curse is Lifted
At the end of this age, after Christ establishes the Kingdom of God on a new earth, “No longer will there be anything accursed, but the throne of God and of the Lamb will be in it, and his servants will worship him” (Rev 22:3), “And night will be no more. They will need no light of lamp or sun, for the Lord God will be their light, and they will reign forever and ever” (Rev 22:5). Does this mean that the sun and moon are gone forever or that the Lord God’s Shekinah glory  will be so bright that even the sun and moon will not be visible? If there is no more sun, how will the vegetation grow? If there is no vegetation growing, what about the food that needs vegetation to be produced? Are these simply comparisons as to how glorious God’s appearance will be, and so much so that we won’t even notice the sun and the moon anymore? Will the seas be literally gone or is death that the sea so often represents what is gone? There simply isn’t enough to go on in these verses to say that the oceans, sun, and moon will be gone forever. It may be a matter of contrast between the glory of God at full strength and the former things that are overshadowed by God’s glory?
When you are experiencing a trial and going through suffering in this present world, the Apostle Paul would have us do a comparative analysis. He wrote, “I consider that the sufferings of this present time are not worth comparing with the glory that is to be revealed to us” (Rom 8:18), and we get a taste of that glory in Revelation chapter 22. No wonder “the creation waits with eager longing for the revealing of the sons of God” (Rom 8:19), since “the creation itself will be set free from its bondage to corruption and obtain the freedom of the glory of the children of God” (Rom 8:21). With this in mind, “we know that for those who love God all things work together for good, for those who are called according to his purpose” (Rom 8:28). Today, we would do well to be “looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God” (Heb 12:2). Jesus looked ahead toward the joy that’s coming, so we should strive to do the same thing; looking forward to a new heaven and a new earth, when all sorrow, pain, suffering, and yes, even death will be gone. If that means the oceans are gone too, so be it; we just don’t know for certain. All we do know is what’s most important and that’s the end of death and the joy that’s set before us is on its way. That much I do know.
Read more here: What Does the Bible Say About Death? 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.