It is one of easternmost peaks of a partly submerged mountain range composed of folded Cretaceous and older rocks that have been cut by granitic intrusions. East-west trending ridges and peaks form the backbone of the island.
Local relief is considerable, and slopes are steep.
This terrain is flanked by marine limestone forming low plateaus with a karsts topography. Rico has a tropical climate. The surrounding oceans and the persistent northeast trade winds maintain almost uniform climatic conditions throughout the year. But there is seasonality in precipitation, with a maximum occurring during the high-sun period, and precipitation varies greatly with altitude and exposure. Temperatures on the south coast average roughly 1F higher.