There generally isn't water in space. It's all collected into planets, or frozen into ice. You have to have land to have water, for the most part. Which is why Lt. Garza almost dropped her caffie when she saw something swim past the starboard viewing bay. She raced to the control deck and brought up the external cams. Sure enough, there was a whole pod of cnidarian creatures swimming alongside the ship. She didn't understand what they were swimming in, but they were clearly pulsating their bodies against something that allowed them to dance and turn about as they floated in the black. They didn't stay too long, the ship's speed seemed to wear them out. Garza spent a few hours checking the Encyclopedia Galactica, but couldn't find any entry on swimming space creatures. She uploaded her data to the unfathomably large category "unidentified encounters", and sighed. Why couldn't the universe grant her enough time to see and learn about all these wonders?