Saladin informs you of a Hive ritual that targeted Ahsa and seemed to injure her. Ahsa has descended into the ocean depths to put a stop to it, with Sloane and Zavala in pursuit. Saladin sends you in after them while he mobilizes the Iron War Beasts.

"We need you in the fight, Guardian."

He transfers the coordinates to your Ghost and orders you to prep for an emergency dive. The hunt is on.