Seacall

Seacall is an lilting, musical language, primarily spoken by merfolk and sea elves. Some sailors pick up bits and pieces of it, but it is rare for mortals to learn in its full.
The language is inherently tied to the flow and splash of water, and carries great power. The few mortals who do master it are often practitioners of sorcerous or eldritch power, who find the primal connections of the language convenient.