The best snorkeling and scuba diving in Costa Rica is right in front of Los Almendros and a little to the right. The reef is full of sea life and only about 4 feet deep. There is a resident sea turtle a little further to the right. Bring your camera, mask, and fins! But if you forget anything, Rocket Frog has it all. It is a good idea to bring sunscreen to Costa Rica. Sunscreen in Costa Rica is much more expensive.
You can Dive with the experts from Rocket Frog. They have new equipment and a great dive boats with experienced instructors. If you have the time they can certify you for diving and they offer open water diving certification. Night dives are available.