Using the Blue Letter Bible site, link below, I found this synonym lexicon by Richard C. Trench in dealing with the 2 Greek words used for sea in the New Testament:‘as you can see Pelagos, πέλαγος, signifies "the vast expanse of open water," where thalassa, θάλασσα, is "the sea as contrasted with the land".’the word in Rev 21:1 is thalassa, θάλασσα, which would seem to indicate that the sea spoken of is NOT the oceans but the Mediterranean.Also keep this in mind Jewish, and even Islamic for what that is worth, tradition is the garden of Eden was in Jerusalem. Since the garden was in the east part of Eden it could be most of Eden was in what is now the Mediterranean and in the new Earth Eden will be restored by the elimination of the Mediterranean sea.xiii.
θάλασσα, πέλαγος .
θάλασσα , But not entering further into this question, it will be enough to say that, like the Latin ‘mare,’ it is the sea as contrasted with the land (Gen. 1:10; Matt. 23:15; Acts 4:24); or perhaps more strictly as contrasted with the shore (see Hayman’s Odyssey, vol. 1. p. xxxiii. Appendix).Πέλαγος , closely allied withπλάξ, πλατύς ‘plat,’ ‘plot,’ ‘flat,’ is the vast uninterrupted level and expanse of open water, the ‘altum mare,’1 as distinguished from those portions of it broken by islands, shut in by coasts and headlands (Thucydides, vi. 104; vii. 49; Plutarch, Timol. 8).2 ...... A passage in the Timoeus of Plato (25 a, b) illustrates well the distinction between the words, where the title ofπέλαγος, Pelagos, is refused to the Mediterranean Sea: which is but a harbour, with the narrow entrance between the Pillars of Hercules for its mouth; while only the great Atlantic Ocean beyond can be acknowledged asἀληθινὸς πόντος ,πέλαγος ὄντως . Compare Aristotle, De Mun. 3; Meteorol. ii. 1:ῥέουσα δ᾽ ἡ θάλαττα φαίνεται κατὰ τὰς στενότητας [the Straits of Gibraltar],εἴπου διὰ περιιέχουσαν γῆν εἰς μικρὸν ἐκ μεγάλου συνάγεται πέλαγος .It might seem as if this distinction did not hold good on one of the two occasions upon which
πέλαγος occurs in the N. T., namely Matt. 18:6: “It were better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea” (καὶ καταποντισθῇ ἐν τῷ πελάγει τῆς θαλάσσης ). But the sense of depth, which undoubtedly the passage requires, is here to be looked for in theκαταποντισθῇ :—πόντος (not in the N. T.), being connected withβάθος, βυθός (Exod. 15:5),βένθος , perhaps the same word as this last,Etym. Note. 9 and implying the sea in its perpendicular depth, asπέλαγος (==‘maris aequor’), the same in its horizontal dimensions and extent. Compare Döderlein, Lat. Syn. vol. iv. p. 75.