Dragon Hole

World’s deepest known undersea sinkhole, 300.89 m deep.

Sima Humboldt and Sima Martel

314 and 248 meters deep, ancient quartzite sinkholes located on the top of forested table-top mountains and containing patches of isolated, primeval rainforest on their bottoms.

Teiq sinkhole and cave

1.25 km long, 1 km wide, and 250 m deep sinkhole with abrupt walls, volume 90 million m³ – the largest sinkhole by volume in the world. Two perennial streams enter the sinkhole and both disappear underground. Contains also a largely unexplored cave.

Xiaozhai tiankeng

Largest sinkhole (tiankeng) in the world, up to 662 meters deep, 625×535 meters across.

Minyé sinkhole and cave

One of the largest and most impressive tiankengs (giant sinkholes) in the world, located in an exotic jungle and crossed by a powerful underground river. Up to 510 meters deep, 350 meters across, volume – 26 million m³. It continues as a cave system. The explored length of cave passages is 5,421 m, maximum depth – 468 m. Contains one of the largest cave rooms in the world – Tuké room, 240 m long, 200 m wide and 130 m high.

Great Blue Hole

A perfectly round undersea sinkhole, 318 meters across and 124 meters deep. Contains tilted stalactites possibly hinting at tectonic movements.

Crveno Jezero – Red Lake

One of the most impressive sinkholes in the world: deep shaft with a lake at the bottom. The total depth of the sinkhole is some 530 m, it contains a 280 – 290 m deep lake with endemic fish.

Sotano de las Golondrinas – Cave of the Swallows

The largest cave shaft in the world – enormous 49 x 62 meters wide hole, 372 meters deep. Famous due to a group of green parrots who have to fly ascending in circles around the cave until they get out of it.

Black Hole of Andros

300 m wide and up to 47 m deep round water filled sinkhole with a layer of violet jelly layer of bacteria at 18 meters depth. Microorganisms have heated up the water to 40°C.

El Zacaton sinkhole

The second deepest water-filled sinkhole in the world. The total depth of the sinkhole is 339 m, the lake is 319 m deep. On the surface of the lake, there are floating several round travertine islands. Lake is formed by volcanically heated acidic groundwater.