Nicaragua is divided into three different Regions

Pacific lowlands:

The Pacific lowland are located around 80 km inland from the coast. It is a flatland except for a couple of new volcanoes of whom some are still active.
In this area we find the largest freshwater lakes in Central America. The lake of Managua (Lago de Managua) and the lake of Nicaragua (Lago de Nicaragua).
The valley of the Río San Juan forms a natural passage across the Nicaraguan isthmus from the Caribbean until the lake of Nicaragua.

Central highlands

The area called central highlands is located up to 1800 m above sea level. You will not find any bigger rivers flowing west to the Pacific. In the north of Managua, the mountains sweep up from sea level in a combination of hillsides, coffee-plantations and pasture, until the border to Honduras and east to the jungles of the interior of Nicaragua.

Caribbean lowland

The eastern Caribbean lowlands of Nicaragua form the extensive and still sparsely settled lowland area with the inviting name “Costa de Mosquitos”. The Caribbean lowlands are occupying nearly 50% of Nicaragua's territory but only very few people live there. .
It is a hot, humid area that includes coastal plains, the eastern spurs of the central highlands, and the estuary of the Río San Juan.