Sierra Negra (Spanish: Black Mountain) is a large shield volcano at the southeastern end of Isabela Island in the Galapagos that rises to an altitude of 1124m.

The surface of Sierra Negra and its neighbouring volcanoes are also covered by young lavas, adding to the difficulty of aging them.

[2] The morphology of Sierra Negra is the upturned soup bowl shape of the other Isabela volcanoes, however it does not have the steep sloping sides that are on others.

[9] While the southern and eastern side of the volcano is covered with lush tropical forest vegetation and fertile soil at moderate altitudes, the higher reaches are more barren with bushes and grasses of modest height of 2–3 meters.

The northern side of the volcano is almost entirely devoid of vegetation (with the exception of some cacti) as it has been resurfaced in more recent times by lava flows.

The habitat for the Sierra Negra giant tortoise, Chelonoidis nigra guentheri, which has a saddleback shell, is on the southern and south eastern slopes of the volcano.

[10] This species is endangered due to population pressure brought on by hunting, habitat alteration, and predation by feral mammals.