A rash guard is a fitted, spandex top that protects beachgoers from the sun and other elements. Surfers typically wear them while they are riding the waves or hanging out on the shore. Sport a rash guard in and out of the water to keep you more shielded from Mother Nature's elements.
You may also be looking for Swimming Design T-shirt
Made 82% nylon, 18% spandex, very comfortable, simple design.