Isla Incahuasi, Ancient volcanic outcrop in Salar de Uyuni, Bolivia

Isla Incahuasi is a rocky volcanic outcrop in the centre of the Salar de Uyuni, at an elevation of 3,656 metres (11,995 feet). It covers 24.62 hectares, with brown and grey lower slopes and ridges densely covered by tall columnar cacti (Trichocereus pasacana). A rectangular building with rough stone walls and a flat earth-coloured roof is built into the rock at its base.

Isla Incahuasi is the summit of an ancient volcano that was submerged when this area formed part of a giant prehistoric lake, roughly 40,000 years ago. The lake later dried, leaving the outcrop standing in the middle of the Salar de Uyuni, which the sources also call salar de Tunupa. The island covers 24.62 hectares and lies at 3,656 metres.

Quechua speakers named the outcrop Inka Wasi, "Inca house"; Spanish sources also record Isla del Pescado, "island of the fish", as an alternate name. The island is often wrongly called Isla del Pescado, which actually lies 22 km to the northwest. A reception centre run by the Llica and Tahua municipalities charges entry for a marked trail across the island.

Visitors reach the island through guided tours departing regularly from Uyuni town throughout the day. The hike on the rock is fairly short, but the terrain is uneven and sturdy footwear is recommended.

Isla Incahuasi is often confused with Isla del Pescado, which lies 22 km to the northwest; the name Isla del Pescado is sometimes wrongly applied to Incahuasi. The island's surface holds fragile coral-like structures and deposits with fossils and algae, remains of a volcano top submerged in a prehistoric lake about 40,000 years ago.