Bay Islands of Honduras
Just off the coast from mainland Honduras, the Bay Islands have been a Caribbean fringe haven since the first pirate needed to hide and disappear. The infrastructure has improved since that time, but where there's a fringe tropical island, you'll always find divers.
Tucked away on the Caribbean coast of Central America, Belize probably has the most dive favorable coastline in the Americas. The world's second longest barrier reef, which stretches nearly 1,000 kilometers/600 miles, officially called the MesoAmerican Barrier Reef, sits right off its coast. The only coral atolls in existence outside of the Pacific are part of Belize and there are dozens of cays on which to castaway.
Unlike other Central American countries, most of the diving off Costa Rica focuses on the Pacific Coast, and off Costa Rica it's a wild west of surprises and diversity. The primary dive area encompasses the Gulf of Papagayo off the sleepy village of Playa del Coco and Playa Hermosa in the Guanacaste region off the Northwest coast. In the middle of the scene is a place called Catalina Island, where almost anything can and will happen.
A true bi-coastal dive destination. On the Caribbean side, Portobelo and Bocas del Toro have been attracting the backpacker, life-escaper crowd for years. The diving is generally shallow off Bocas and a little deeper off Portobelo, and easy and inexpensive. On the Pacific side, liveaboards access the wild and wooly diving in the protected Coiba National Park, which includes Isla Coiba and the waters off smaller surrounding islands.