About 30 sq km of coral reefs are situated along the southern portion of Costa Rica’s Caribbean coastline. They are situated where hardrock promontories interrupt the high energy shoreline in three distinct zones: between Moin and Limon; Cahuita; and between Puerto Viejo and Punta Mona. 
According to the Reefs at Risk analysis, all of Costa Rica’s reefs are threatened by human activities. Both overfishing and sedimentation were rated as threatening all reefs, while coastal development was estimated to affect over 85 percent of reefs. Marine-based pollution was estimated to be a threat to nearly a quarter of reefs.
The main cause of damage to Costa Rica’s reefs is the excess of sedimentation from logging, land clearing and agriculture,  such as banana plantations. Pressure from coastal populations also poses a threat to the reefs through sewage discharge and coastal development. Uncontrolled tourist activity is a significant and growing problem from the associated coastal development to The direct impact of swimmers and snorkellers , anchor damage from tourist boats, and in general the coastal development associated with uncontrolled tourist activity are all significant and growing problems.
Elevated water temperatures during the 1982/83 El Ni