Dragon Hole
![Dragon Hole with expedition vessels](https://www.wondermondo.com/wp-content/uploads/2017/09/DragonHole.jpg)
World’s deepest known undersea sinkhole, 300.89 m deep.
Sima Humboldt and Sima Martel
![Sima Humboldt and Sima Martel, sinkholes in Venezuela](https://www.wondermondo.com/wp-content/uploads/2017/10/Sarisarinama.jpg)
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
![World's deepest sinkhole - Xiaozhai tiankeng, with tourist route visible](https://www.wondermondo.com/wp-content/uploads/2017/10/XiaozhaiTiankeng.jpg)
Largest sinkhole (tiankeng) in the world, up to 662 meters deep, 625×535 meters across.
Minyé sinkhole and cave
![Crossection of Minyé sinkhole, compared with Boeing 747-400, Papua New Guinea](https://www.wondermondo.com/wp-content/uploads/2017/10/Minye.jpg)
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
![Great Blue Hole, Belize](https://www.wondermondo.com/wp-content/uploads/2017/10/GreatBlueHole.jpg)
A perfectly round undersea sinkhole, 318 meters across and 124 meters deep. Contains tilted stalactites possibly hinting at tectonic movements.
Crveno Jezero – Red Lake
![Crveno Jezero sinkhole, lake](https://www.wondermondo.com/wp-content/uploads/2017/09/CrvenoJezero3.jpg)
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
![Caver rappelling down into the Sótano de las Golondrinas, Mexico](https://www.wondermondo.com/wp-content/uploads/2017/10/Golondrina2.jpg)
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
![Cross section of South Andros Black Hole in south-north direction, compared with Boeing 747-400](https://www.wondermondo.com/wp-content/uploads/2017/09/BlackHole.jpg)
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
![El Zacaton and Nacimiento spring](https://www.wondermondo.com/wp-content/uploads/2019/10/ElZacaton-1-1200x721.jpg)
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.