“The deepest cave drop in the continental United States is found underneath Pigeon Mountain in Georgia. The “Fantastic Pit” in Ellison’s Cave drops 586 vertical feet.”
“Emperor penguins can dive to 1,850 feet (564 meters)—deeper than any other bird—and stay underwater for more than 20 minutes.”
“Hang Son Doong, the “mountain river cave” in Vietnam, may be the world’s biggest subterranean passage. A half-mile block of 40-story buildings could fit inside this stretch of the cave”
“In April 2005 Croatian freediver Kristijan Curavic plunged to 168 feet (51 meters) below the North Pole, the deepest dive ever made in the Arctic.”
“Spelunkers rappel 300 feet (91 meters) into the Greenland ice sheet. Glacier caves such as these form when seasonal meltwater or geothermal vents cut fissures and channels through an ice sheet.”
Source : Exploring the Deepest Recesses of the Planet - National Geographic
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