They (Ibid. 1:14) "embittered their lives with hard toil, with mortar"; You, likewise, made the water like slime for them, and they sank in it. Thus (15:4) "They were mired in the Red Sea," "mired" connoting slime, as in (Psalms 69:3) "I am sunk in the slime of the depths," and (Jeremiah 38:6) "and Jeremiah sank in the slime." Thus, "they were mired in the sea."