Isla Catalina sits 1.5 nautical miles off the southeastern shore of Hispaniola, a low coral platform whose fringing reefs hold visibility that regularly exceeds 30 meters. The island became part of Parque Nacional Cotubanamá in 1975, shielding 9.6 square kilometers of marine habitat from coastal development and securing nursery grounds for queen conch, spiny lobster, and juvenile parrotfish. No permanent human settlement exists on the island; the single beach landing—a crescent of crushed coral backed by sea grape and buttonwood—operates under conservation protocols that limit daily visitor numbers and prohibit anchoring inside the reef crest. Catalina Island dive tours depart Punta Cana and Bayahibe between 09:15 and 10:00, crossing the Canal de la Catalina aboard catamarans or twin-hulled dive tenders. The western reef wall descends from three meters to 18 meters in a series of spur-and-groove formations, channels scoured by winter swells that now harbor elkhorn coral colonies, barrel sponges the height of a diver, and schools of blue tang that shift in coordinated waves. Snorkelers work the shallows above the reef flat, where brain coral heads and staghorn thickets rise within arm's reach of the surface. Scuba routes follow the wall south toward Punta Cana, a 40-minute drift that passes cleaning stations attended by Spanish hogfish and a resident population of southern stingrays. The reef's health reflects Cotubanamá's long enforcement history. Spearfishing has been prohibited since 1983; mooring buoys installed in 1998 eliminated anchor damage across 14 dive sites. Nassau groupers, locally extirpated from many Caribbean reefs, reappeared in Catalina's ledges in 2004 and now form aggregations of 20 or more individuals during summer months. Hawksbill turtles forage among the gorgonians; loggerheads transit the channel between June and September. The seabed around the island holds scattered ballast stones and iron fittings from colonial-era wrecks, though no intact hull sites have been surveyed. Conservation fees collected from tour operators fund ranger patrols and quarterly reef health assessments conducted by the Instituto de Investigaciones Marinas.