The Bat Islands are one of the premiere scuba diving destinations in Costa Rica. Located in the far north of the Guanacaste off the coast of Santa Rosa National Park. The area has been protected as a marine preserve by the country as part of the national park. The Bat Islands are full of marine life. There are huge schools of different species of fish ranging in size from small to huge. There are also massive schools of Rays that pass through the area. For divers, the area is most famous for the encounters that you can have with the very large bull shark!

Source: https://www.scuba-dive-costa-rica.com