(thalassa hualine; Re 4:6; 15:2): In the vision of heaven in these two apocalyptic passages a "glassy sea" is seen before the throne of God. The pure translucency of the sea is indicated in the former reference by the words, "like unto crystal"; and the fiery element that may symbolize the energy of the Divine holiness is suggested in the latter passage by the trait, "mingled with fire." On the margin of this sea--on the inner side--stood the victorious saints, with harps, singing the song of Moses and of the Lamb (Re 15:2-4). The imagery here points to a relation with the triumphal song in Ex 15:1-27, after the deliverance from Pharaoh at the Red Sea. It is not easy to define the symbolism precisely. The sea, reflecting in its crystalline depths the purity and holiness of the Divine character and administration, speaks at the same time of difficulties surmounted, victory obtained and safety assured, the after-glow of the Divine judgments by which this result has been secured still illuminating the glassy expanse that has been crossed.
James Orr