The southeast half of the island consists of Volcán Maderas, which has a crater lake and supports a diverse rainforest environment. Maderas is also believed to have risen in the Holocene epoch and rises above sea level. It is considered extinct or possibly dormant. The large lagoon in its crater was discovered on April 15, 1930, by the farmer Casimiro Murillo. The sides of the volcano are mainly covered with coffee and tobacco plantations while the remainder is rain forest. Much of this part of the island is now a nature reserve.