Type: Sinkhole
Location: Numby Numby, Australia’s Northern Territory
Depth: 200 feet
Brief description/events highlight, etc: It is surrounded by high cliffs. The water reaches a depth of about 60 meters and provides a good environment for swimming since the water source comes from a hot spring hidden which brings the water to a steady 32 degrees Celcius (90 Fahrenheit).



Type: Depression
Location: Qattara, West of Cairo, Egypt
Depth: 436 feet
Brief description/events highlight, etc: The largest natural depression in the world, measuring 80km long by 120km wide. This dangerous, sludge-filled quicksand pit is unearthly in its appearance and shocking in its size. The 133m deep sinkhole has been used in battle and more recently scientists have attempted to develop a $360 million dollar project that would harness the Qattara for complete energy independence.



Type: Sinkhole
Location: near Rocksprings, Texas
Depth: 400 feet
Brief description/events highlight, etc: The Devil’s Sinkhole is a collapsed underground cavern in the relatively flat, hard limestone of the Edwards Plateau. Since 1985 the property has been a State Natural Area. As such the public access has been limited to preserve its many unique qualities. Today the Sinkhole is the summer home to one to four million Mexican Free-tailed Bats (a subspecies of the Brazilian Free Tailed Bat). It is an amazing sight at sundown when they begin to come out, a few at first then more and more until they become a swirling mass.



Type: Sinkhole
Location: Sarisarinama, Venezuela
Depth: upto 1,148ft
Brief description/events highlight, etc: These sinkholes are made more distinctive by where they appear; they lie on top of high mesas in the country's tepui region. Tepuis are incredibly isolated areas filled with lush forests and waterfalls. Sarisarinama sinkholes were first discovered in 1974, high up on flat-topped tepui mountains, and have been described as part of a "lost world".