The Great Outdoors photo contest is still accepting entries until the 29th of April. There is a beach and underwater specific category to this contest.
The contest is open to professionals and amateurs alike. Judges include Elizabeth Krist of National Geographic, Justin Appenzeller of Outdoor Life and Jon-Paul Harrison of Tandem Stills + Motion. Categories include Landscapes, Wildlife and Insects, Action and Adventure, and Beaches and Underwater.
Find the full contest details here.