Phong Nha – Ke Bang cave system (Hang Khe Ry)

Entrance in Phong Nha cave, Vietnam

Some 20 km long cave with a very long underground river (13,969 m) with sandy beaches. Cave contains valuable archaeological artifacts of Champa culture including beautiful ceramic vases.

Paradise Cave (Thien Duong Cave)

Paradise Cave (Thien Duong)

31.4 km long cave with some of the most beautiful cave formations, cave rooms are up to 150 m high. Endemic scorpion Vietbocap thienduongensis lives in the cave.

Víðgelmir

Víðgelmir

Largest (by volume) lava tube cave in the world. 1,585 meters long cave , with volume 148 000 m³. Contains ice formations, evidence of habitation, possibly from the Viking Age.

Surtshellir

Surtshellir

Longest known lava cave in Iceland, 1 970 m long. Ghost stories.

Grjótagjá

Grjótagjá

Small lava cave with thermal spring and hot lake inside. Earlier the lucid water in the cave was suitable for bathing but in 1975 – 1984 the temperature of water in it exceeded 50° C.

Volusia Blue Spring

Manatees in Volusia Blue Spring

Volusia Blue Spring is a 1st magnitude spring that beats from a large fissure – a cave that has been dived up to 38 m deep. Habitat of manatees.

Callao Cave

Callao Cave, Philippines

An enormous cave system with beautiful speleothems. Here have been found the earliest human remains in the Philippines, at least 67 thousand years old. These remnants belong to an extinct species of humans – Homo luzonensis.

Aouk-Kladuk Underground River

Kladuk River in the Kladuk Abyss

World’s most powerful underground river. Aouk-Kladuk Underground River is some 1.5 kilometres long. The stream has a volume of 130 – 180 cubic meters.

Keek sinkhole

Keek Sinkhole, Aouk Underground River

One of the tiankengs of Aouk Underground River. Keek sinkhole is bell-shaped hollow that is some 160-180 m deep, its volume is 1.4 million cubic meters.

Hafasu Tiankeng

One of the tiankengs of Aouk Underground River. Hafasu Tiankeng is some 100 m deep, with a volume of 12 – 15 million cubic meters.