Somewhere in your family tree swims an Elemental tied to the Seas this has granted you a few benefits. 

• You gain a swimming speed equal to your walking speed.
• You gain the ability to breath underwater.
• You gain the Shape Water cantrip as well as the Ice Knife spell. You can cast Shape water at will and Ice Knife a number of times equal to you proficiency bonus without material components. You regain uses after a short rest and can cast them with any spell slots you may have.