The Caribbean coast, known as the Mosquito (or Miskito) Coast or Mosquitia, consists of low, flat, wet, tropical forest, extending into pine savannas 80–160 km (50–100 mi) inland. The coastal lowland rises to a plateau covering about one-third of the total area. This plateau is broken by mountain ranges extending eastward from the main cordillera to within 64–80 km (40–50 mi) of the Caribbean coast. The mountainous central area forms a triangular wedge pointed southeast, rising at its highest to some 2,000 m (6,600 ft). The plains and lake region, in a long, narrow structural depression running northwest to southeast along the isthmus, contains a belt of volcanoes rising to 1,500 m (5,000 ft) and extending from the Gulf of Fonseca to Lake Nicaragua. In this region is located Lake Managua, at 41 m (136 ft) above sea level, which drains through the Tipitapa Channel into Lake Nicaragua, at 32 m (106 ft) above sea level, which, in turn, drains through the San Juan River eastward into the Caribbean. Lake Nicaragua is about 160 km (100 mi) long and 65 km (40 mi) wide at the widest point, while Lake Managua is 52 km (33 mi) long by 25 km (16 mi) wide.
The principal waterways are the Coco (or Segovia) River, navigable up to 240 km (150 mi) inland from the eastern Mosquito Coast, and the San Juan, navigable to within a few miles of the Caribbean, where a series of rapids halts transportation.
Nicaragua lies in an earthquake zone.