Funnels invariably attract researchers and tourists. Although the study of the largest karst formations can be extremely dangerous people, it does not take away.
Sinkholes — some of the most incredible forms of relief. They are formed due to the movement of soil in karst, that is soluble in water, rocks. When groundwater dissolved and leached rock formations, the earth sags — and there is a funnel. The depth does not exceed one meter, others go into the ground for tens and hundreds of meters.
Text of National Geographic Russia
1. Red Lake — karst lake that filled 530-meter deep crater in the south of Croatia. It was formed as a result of the collapse of a large set of underground caves. There is a theory that the lake is connected by underground streams with all the other lakes and rivers of the area.
2. The total depth of the crater — about 530 meters, and its volume — about 25-30 million cubic meters. Thus, it is one of the largest sinkholes in the world.
3. Bimmen in Oman — a relatively small crater about 30 meters deep, but its bottom is filled with crystal clear water. Of course, she immediately became a magnet for tourists.
4. The depth of the well Bimmen is about 20 meters. Under water tunnel is 500 meters long, which connects the sinkholes to the sea and fresh water mixes with the sea here.
5. Darwaza , also known as «The Gates of Hell» — a funnel with a diameter of 70 meters and a depth of located in Turkmenistan. Soviet geologists set fire pit with natural gas back in 1971, hoping that it will burn for a couple of days. The flame died down so far.
6. crater diameter is approximately 60 meters, depth — about 20 meters. The gas comes out of the ground, splitting into hundreds of different-sized burning torches. In some flares flames reach 10-15 meters in height. clickable:
7. For details, see the article » The gates of hell. Turkmenistan «.
8. Sima Humboldt — funnel in Venezuela depth of about 320 meters with almost vertical walls. It named after the German scientist and traveler Alexander von Humboldt. Forest grows abundantly, not only around the crater, but also within it.
9. The failure of almost circular shape is incident on a depth of 314 meters, and the funnel volume is 18 million cubic meters. The upper edge of the dip is 352 meters wide and the bottom reaches 502 meters. Thanks to the vertical walls, at the bottom of the funnel has developed its own, unique ecosystem, with the species of plants and animals that are found nowhere else on Earth.
10. Syaochzhay Chanko , aka Heavenly pit, the deepest sinkhole in the world — 660 meters deep and 530 wide. One of the most popular tourist destinations in China. It is advised to visit during seasons of heavy rains, because then with the edge of the funnel into the drain beautiful waterfalls.
11. To scale: Heavenly Pit and 747.
12. The Great Blue Hole — an underwater sinkhole near-perfect round shape, depth of 120 meters and 300 meters in diameter. Opened the famous explorer Jacques-Yves Cousteau, to include it in the list of the 10 best places for diving.
Geological formation 13. This system was originally limestone caverns formed in the last glacial period. Sea levels then were much lower, but when the ocean rose and submerged arch of the cave collapsed, formed sinkhole.
At high tide at the site of the great blue hole, the present whirlpools, draws in all floating on the surface: the algae, the board boats. Often, in these eddies, people are dying. With the advent of low tide hole begins spewing out themselves powerful water fountains.