Weirdest holes on earth

The holes in this video are all completely natural phenomena - but that doesn't mean that they're not completely puzzling and, er, downright weird, actually.

This video shows some of the world's most bizarre sites - the weirdest holes on earth, including:

Morning Glory Pool, Yellowstone National Park

This thermal pool gets its bright colour from the algae that grows in it, and its name comes from its resemblance to the morning glory flower. However, thanks to tourists at Yellowstone the colour of the Morning Glory Hole has begun to change over the years. Visitors have been throwing rubbish and coins into the hole affecting the temperature and bringing the yellow colour from the outskirts into the centre.

Darvaza Crater, Turkmenistan

In the heart of the desert lies the Darvaza Crater, also known as the 'Burning Gates' or the 'Door to Hell'. It was created by a Soviet drilling accident in the 1950s. Scientists then set it on fire to try and burn off the noxious gases, and it's been burning ever since. According to the Smithsonian Magazine the geologists drilled over a 'cavernous pocket of natural gas' and when the site collapsed a number of other craters were also opened.

Monticello Dam, California

This spillway in California is the largest in the world and it can handle 362,000 gallons of water every second but it's definitely not a safe space to swim, in fact in 1997 a student got sucked in and drowned. Although you are able to see the hole from the lake, the area is sectioned off for safety reasons. According to Atlas Obscurer, the dam and spillway were both constructed in the 1950s.

Great Blue Hole, Belize

This is believed to have been created by sea level rise during the last Ice Age, it's nearly 1,000 feet wide and more than 400 feet deep. The Great Blue Hole is believed to be the largest sea hole in the world. According to the website, the hole was originally a limestone cave that would have initially formed 150,000 years ago.