Lake Kaindy
Lake Kaindy is situated 2,000 meters above sea level. It was created by the result of an enormous limestone landslide.
Jeita Grotto
The Jeita Grotto is a compound two separate but interconnected limestone caves spanning an overall length of nearly 9 kilometres. The caves are situated north of the Lebanese capital Beirut. Though inhabited in prehistoric times, the lower cave was not rediscovered until 1836. It can only be visited by boat since it channels an underground river that provides fresh drinking water to more than a million Lebanese.
Yucatán underwater caves
In the jungles of Yucatán Peninsula, crystal clear cenotes fuel their surrounding ecosystems with fresh water. Numbering in the thousands, these flooded sinkholes are unique to this region of Mexico, and were principal water sources for many Maya settlements.
Atolls
An atoll is an island of coral that encircles a lagoon partially or completely.
Ecological dead zones
Dead zones are low-oxygen areas in the world's oceans, the observed incidences of which have been increasing since oceanographers began noting them in the 1970s. There are 146 dead zones in the world's oceans where marine life can't be supported due to depleted oxygen levels. Some of these are as small as a square kilometre, but the largest dead zone cover 70,000 square kilometres.
Chinese scholar rocks
Chinese scholar rocks are small shaped or naturally-occurring rocks appreciated by Chinese scholars from the Song dynasty onwards, and quite frequently found in traditional Chinese gardens.
Loki’s Castle
Loki's Castle is a field of five active hydrothermal vents in the mid-Atlantic ocean.
Year Without a Summer
Missing rings are rare in oak and elm trees - the only recorded instance of a missing ring in oak trees occurred in the year 1816, also known as the Year Without a Summer.
Tsingy de Bemaraha
Tsingy de Bemaraha is a national park in Madagascar. The Tsingys are karstic plateaus in which groundwater has undercut the elevated uplands, and has gouged caverns and fissures into the limestone.
Surtsey
Surtsey is a volcanic island off the southern coast of Iceland. It was formed in a volcanic eruption which began 130 metres below sea level, and reached the surface on 14 November 1963.