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A map of Krubera Cave: the deepest cave on earth, going down more than 2000 meters under the earth with air and waterfalls all the way down. It takes more than a month to reach the bottom. [640×1441](r/MapPorn)
This is a great question. There are all sorts of extreme technical challenges associated with spelunking. In many ways, spelunking deep caves is much more difficult than high peak mountaineering.
For one, the amount of equipment needed far exceeds that of mountaineering. A deep expedition will use specialized camping gear, food, lights, SCUBA re-breathers, suspension gear and literally miles of rope.
The spelunkers must go slowly as mistakes/injuries put the everyone in the expedition in danger. Think about how difficult it would be to have to haul a non-ambulatory person out from the bottom of a cave.
It’s dark and cold. Spelunkers do not use their lights unless absolutely necessary to save on power. This slows everything down.
It’s also very wet. These caves are filled with flowing water howling winds. Spelunkers are constantly soaked. The nature of caves ensures that no permanent base camps can be set up. The water will destroy anything you leave down there, so every time they go in, they essentially must start all over.
And I haven’t even touched on sumps yet. Caves are just basically massive water conduits. Every so often they form what they call sumps. They look like pools but really there are completely flooded sections of the cave, beneath the water’s surface. That’s why they need the re-breather equipment, because once you hit a sump, you have to swim through it. Navigating sumps is the most dangerous part of spelunking.
If you, or anyone else, truly are interested in this then I recommend checking out Blind Descent. It goes into great detail on just how truly difficult it is to explore these caves. It also details the rare breed of person that takes on the challenge of exploring the deep caves. One of the most fascinating books I have ever read.