The Greek thalassa (G2281) is the sea β in Scripture not merely a geographical feature but a theological symbol. The OT sea represents primordial chaos (Genesis 1:2: 'the deep'), divine power (Job 38:8-11: 'Who shut up the sea behind doors?'), and the realm of danger and death. Jesus walking on the sea (Matthew 14:25) and stilling the storm (Mark 4:39) demonstrate His dominion over chaos. The Sea of Galilee (thalassa) is the arena for many of Jesus' miracles and the calling of His disciples.
Thalassa carries eschatological weight in Revelation, where the 'sea' gives up its dead (Revelation 20:13) and, in the new creation, 'there was no longer any sea' (Revelation 21:1). The disappearance of the sea in the new creation is not the elimination of water but the end of the chaos, danger, and separation it represents. The new Jerusalem needs no sea because there will be no more separation, no more threat, no more death. Meanwhile, in the present age, the sea of glass before the throne (Revelation 4:6, 15:2) represents the tamed chaos β the thalassa brought under God's sovereign peace.