The Gulf of Fonseca is an extension of the Pacific Ocean, considered “a true internal sea” located between 12° 54’ y 13° 30’ North Latitude and 37°00’ y 88°00’ West Latitude. The Gulf of Fonseca and its coast have an approximate area of 5,776 square kilometers, located in the extreme south of the departments of Valle and Choluteca, climate conditions are determined by atmospheric phenomena of the tropic and sub-tropic. The average temperature of the lower area is 38 degrees centigrade and 21 degrees centigrade in the higher areas. The highest temperatures are during March and April, and the lowest during November and December. Average annual precipitation varies between 1,500 and 2,000 millimeters (mm).
The mouth of the gulf has an area of 19.33 nautical miles (35 km) that extends in a straight line from Punta de Amapala in El Salvador to Punta Cosiguina in Nicaragua.
The most important hydrographic system that flows into the Gulf of Fonseca is the Choluteca River with a watershed of 7,664 kilometers. Of the 112,492 Km2 of the national territory, the area of the slope from the Pacific that drains the Gulf of Fonseca is approximately 15,000 Km2 (13.38%).
The mangrove forest existing in southern Honduras is located in the coastline of the departments of Valle and Choluteca, which has a surface of 713.3 Km2 (49% of the mangrove forest in Honduras), which are periodically washed by the 65 existing estuaries (24 in the Bay of Chismuyo, 19 in the Bay of San Lorenzo and 22 in the Bay of Fonseca). The mangrove community is described as coastal hydrophilic vegetation formed by brushwood forests and existing 3 types of mangrove in belts, dense or low.
The Bay of Fonseca was discovered by the Spaniards in name of the Spanish Crown, which had sovereignty over the territory for almost 300 years. Afterwards, another state took over for 14 years, the Federal Republic of Central America. Three countries within the coastal line of the Bay substituted the territorial sovereignty of the Federal Republic.