This area of river valleys and coastal plains, which most Honduras call "the north coast," or simply "the coast," has traditionally been Honduras's most exploited region. The central part of the Caribbean lowlands, east of La Ceiba, is a narrow coastal plain only a few kilometers wide. To the east and west of this section, however, the Caribbean lowlands widen and in places extend inland a considerable distance along broad river valleys. The broadest river valley, along the Río Ulúa near the Guatemalan border, is Honduras's most developed area. Both Puerto Cortés, the country's largest port, and San Pedro Sula, Honduras's industrial capital, are located here, as is La Ceiba, the third largest city in the country.
To the east, near the Nicaraguan border, the Caribbean lowlands broaden to an extensive area known as the Mosquitia. Unlike the western part of the Caribbean lowlands, the Mosquitia is Honduras's least-developed area. Underpopulated and culturally distinct from the rest of the country, the area consists of inland savannah with swamps and mangrove near the coast. During times of heavy rainfall, much of the savannah area is covered by shallow water, making transportation by means other than a shallow-draft boat almost impossible.