Swimming at night, especially in the ocean, is an important part of my training for the English Channel. Safety is the first concern. Always have a spotter. I like to wear a yellow glow stick ( 3 inch) on the back of my swim cap and suit. My spotter wears a glow stick, too, so we can easily see each other. Also, swim in a safe zone away from boat traffic. My favorite place for a night swim is Pine Point (Maine). I will swim parallel to shore. Wear clear lens goggles-- NEVER wear tinted goggles at night because it will reduce your visibility.
Mental preparation for a night swim is extremely important. A swimmer needs to stay focus on positive thoughts. If your mind starts to wander down the path of the movie "JAWS", stop those frightening thoughts immediately and re-focus. Swimming at night is absolutely beautiful, especially if you're lucky enough to see a bio luminescent show ---light produced by a reaction of algae to water movement(swimmer). It's spectacular! Pine Point Beach offers one of the very best "light" shows for night swimmers. Remember to stay safe, think positive thoughts, and enjoy.