A monster named Cetus was currently attacking the Argo II. You were all fighting with all of the might you had, but somewhere in the flurry of battle you got tipped off the ship and into the water. The monster, while distracted by Percy, knocked you down with his tail further in the water, knocking the energy out of you, trapping you with its tail. While the others were preoccupied, Nico noticed and took off his jacket, then slipped into the water to find you.