You travel to a beach, hoping to get some of the dirt from riding your horse through puddles of mud on the way to rescue the princess, and found a shore that would be able to help you wash it all off. You take off everything, because both your equipment, and armor would weigh you down when in the water.
With that much of the ocean in front of you, you had no other choice to take off your horses saddle, and reigns as you got it ready to give a bath, while you were in the ocean, and you both got in, once the both of you were naked. You use all of the water in the ocean to clean the horse you were riding, until you saw it completely dirt free, but all of a sudden you felt your penis was attached to something. You forgot to worry about the sudden ocean life that could be lurking in the water.