The Greek noun phrase ἡ θάλασσα can be rendered "the sea." Commentator J. Ramsey Michaels (going from memory here) reports that John uses "sea" language some 26 times with varying nuances. The first occurrence is apparently Revelation 4:6:
καὶ ἐνώπιον τοῦ θρόνου ὡς θάλασσα ὑαλίνη ὁμοία κρυστάλλῳ· καὶ ἐν μέσῳ τοῦ θρόνου καὶ κύκλῳ τοῦ θρόνου τέσσερα ζῷα γέμοντα ὀφθαλμῶν ἔμπροσθεν καὶ ὄπισθεν. (Nestle 1904)
Here, John perceives what appears to be a glass sea likened to crystal. It is clear that sea does not refer to the wicked sea of humankind in this context; that particular understanding of the word "sea" in Rev. 4:6 leads to interpretational absurdities. Granted, there are a number of scholars who desire to construe the "sea" (even in the throne-vision scene) in harmony with combat motifs. Christopher A. Davis believes that the "sea" of Rev. 4:6 tries to oppose God, but he exercises sovereignty over this figurative body of water. Yet I am more convinced that Revelation uses temple imagery in 4:6. See Buchanan, George Wesley.
The Book of Revelation: Its Introduction and Prophecy. Eugene, Oregon: Wipf & Stock, 2005, Page 155. Compare Revelation 15:2.
Another set of verses indicating that the "sea" does not always depict evil, wicked humanity or forces opposed to God is Revelation 10:2-8.
Revelation 10:2: καὶ ἔχων ἐν τῇ χειρὶ αὐτοῦ βιβλαρίδιον ἠνεῳγμένον. καὶ ἔθηκεν τὸν πόδα αὐτοῦ τὸν δεξιὸν ἐπὶ τῆς θαλάσσης, τὸν δὲ εὐώνυμον ἐπὶ τῆς γῆς,
A strong angel places his right and left feet upon sea and earth respectively. What does the sea represent in this context? Anthony Charles Garland believes that the sea and land together depict the entire globe, not necessarily alienated humanity. See https://www.jstor.org/stable/25765969?seq=1#page_scan_tab_contents
Revelation 10:5 refers back to the angel, who stood astride sea and land: Καὶ ὁ ἄγγελος, ὃν εἶδον ἑστῶτα ἐπὶ τῆς θαλάσσης καὶ ἐπὶ τῆς γῆς, ἦρεν τὴν χεῖρα αὐτοῦ τὴν δεξιὰν εἰς τὸν οὐρανόν
In a similar vein, the resurrected Christ proclaimed that all authority had been given him in heaven and on earth. Matthew Poole understands the angel in Rev. 10:2ff to be Christ.
The Pulpit Commentary offers these remarks on Rev. 10:2:
And he set his right foot upon the sea, and his left foot on the earth. Thus it is indicated that the revelation which is to follow affects the whole world, and is not partial in its operation, as were the judgments set forth under the earlier trumpets. Wordsworth (following Hengstenberg) sees in the earth an emblem of worldly power, and in the sea a symbol of the agitation and turbulence of nations.
While the sea, understood as turbulent or wicked humankind cannot be ruled out, I don't believe Hengstenberg's is the most probable explanation.
From
The Expository Notes of Dr. Thomas Constable:
The angel stood astride the earth and the sea symbolizing his authority over the whole world ( Revelation 10:5; Revelation 10:8; Revelation 7:2; cf. Exodus 20:4; Exodus 20:11; Deuteronomy 11:24; Psalm 68:22; Psalm 69:34). The implication is that his message involves the whole world. Other less likely views, I think, are that his stance symbolizes the universality of the message, [Note: Morris, p137.] or that he was defying the sea"s instability. [Note: Swete, p127.]
13:1-2 discusses a great sea beast that arises from the "sea" having seven heads and ten horns. The sea (ἡ θάλασσα) undoubtedly represents that mass of humanity alienated from God--the mass that stands in opposition to him (i.e., the turbulent wicked). See Isa. 57:20-21.
The beast in John's vision has features resembling a leopard, bear, and lion. We find similarities in Daniel 7:3-8 where four beasts arise from the "sea," each one being divergent from the other: the prophet saw one beast comparable to a lion with the wings of an eagle. That same beast stood up like a human and was given the heart of a human. Another beast reminded Daniel of a bear while yet another beast was akin to a leopard with four wings. Finally, the fourth beast of Daniel's vision was "terrifying and dreadful and exceedingly strong" (ESV). The dragon likely gave power and authority to these beasts too.
See http://digitalcommons.andrews.edu/cgi/viewcontent.cgi?article=1761&context=dissertations
Revelation 20:13 speaks of death, Hades, and the sea giving up the dead in them. What is the "sea" in 20:13? Does it refer to the natural sea (a literal body of water) or is the sea symbolic in this case? In view of how sea is used elsewhere by John, I cannot help but wonder if the "sea" of 20:13 is identical with the sea of Revelation 21:1. Understanding "sea" to mean the same thing in both cases would help us to make sense of the expression at 21:1, "and the sea was no more."
I think the
Revelation Climax book does not explain the sea of Revelation 20:13 to be identical with the "sea" in 21:1. Hence, I reserve judgment until such a change is made.
The
Insight book (1:1015-16) gives this explanation:
The sea (which at times serves as a watery grave for some) is mentioned in addition to Hades (the common earthen grave), for the purpose of stressing the inclusiveness of all such dead ones when Revelation 20:13, 14 says that the sea, death, and Hades are to give up or be emptied of the dead in them. Thereafter, death and Hades (but not the sea) are cast into “the lake of fire,” “the second death.” They thereby figuratively ‘die out’ of existence, and this signifies the end of Hades (Sheol), the common grave of mankind, as well as of death inherited through Adam.