Nicaragua has disputed Costa Rica’s territorial rights to free use of the Río San Juan, while Costa Rica disputes Nicaragua’s claim that the river is entirely Nicaraguan territory. The 205-kilometer-long (127-mile-long) river, which flows from Lago de Nicaragua to the Caribbean, marks most of the border between these countries. When you are on the water, you are inside Nicaragua.
The important proviso was that non-Costa Rican passengers aboard Costa Rican vessels using the river are not required to obtain Nicaraguan visas.Costa Ricans have had right of commercial use of the Río San Juan, but since 2001 Nicaraguan authorities have boarded Costa Rican boats and fined foreigners aboard ($25) for using the river without Nicaraguan visas. This has primarily affected sportfishing boats from Costa Rican lodges in Barra del Colorado, and tour boats and water taxis operating from Los Chiles.
In 2009 the International Court of Justice adjudicated on access rights to the river. Essentially it reaffirmed an 1858 treaty that acknowledged Nicaragua’s ownership of the river while guaranteeing Costa Ricans free access. The important proviso was that non-Costa Rican passengers aboard Costa Rican vessels using the river are not required to obtain Nicaraguan visas. Both countries accepted the verdict, which also granted Nicaragua the right to build an interoceanic canal if it compensated Costa Rica for the damage. However, Costa Rica’s militarized police force will no longer be permitted to patrol the river, which is also an avenue for drug trafficking. The two nations actually came to blows over this issue in 1998. The ruling paved the way for increased tourism along the river, which is bordered by the Refugio de Vida Silvestre Corredor Fronterizo (Frontier Corridor National Wildlife Refuge).
Just as the dust settled, in November 2010, Nicaragua’s leftist president, Daniel Ortega, decided to fan the nationalist flames by accusing Costa Rica of wanting to seize the river. This came after Costa Rica appealed to the Organization of American States (OAS) to intervene after Nicaraguan dredging of the river intruded onto Isla Calero, in Costa Rican territory, and Nicaraguan troops occupied Costa Rican soil.
Excerpted from the Tenth Edition of Moon Costa Rica.