Korocobos islands

This is an island chain among the "Thousand Islands" in a world I created for a D&D campaigns. This collection of islands is considered one of the worst areas of sailing in the world, it's numerous whirlpools, underwater reefs, and treacherous rocks make it almost impossible to navigate without a pilot from the Korocobos islands itself. The true inhabitants of the islands aren't the pirates that live upon them, but the merfolk who live under the waves! The islands represent one of the three Black Market Hearts among this world where almost anything is available for the right price.