en_tn_condensed/isa/51/15.md

who churns up the sea

This speaks of Yahweh causing the sea to move and the waves to rise and fall as if he were stirring the sea as one stirs the contents of a bowl with a large spoon. Alternate translation: "who causes the sea to churn" or "who makes the sea move up and down" (See: rc://en/ta/man/translate/figs-metaphor)

Yahweh of hosts

See how you translated this name for Yahweh in Isaiah 1:9.