Searching the world’s most exciting adventure spots, my undaunted spirit brings me to one little-known gem that lies hidden beneath the Earth’s surface located some 25 km outside the town of Bonito, the eco-adventure capital of Brazil.

Abismo Anhumas

Abismo Anhumas (Anhumas Abyss) is exactly what the name suggests: a dark abyss with a deep lake on the bottom. Rappelling down a vertical shaft the height of a 26-story building is the only way to access this subterranean cave.

The adventure begins the evening before with a short rappelling session on a gym wall in Bonito.  Training completed,  I sign my life away stating that I’m aware of the risks of rappelling and I am sane. Some say rappelling and some say abseiling; it’s both the same thing and involves dangling. And it’s only while I’m dangling on a rope through a crack in the rock 72 meters above an underground lake that I begin to seriously question my sanity.

Image credit: Geert-Leysen

Uhmm…well, I’ve passed the point of no return. Safety-tied together with another girl, we slowly slide down to oblivion as we release the rope brake in a controlled manner to let the rope slide through the pulley. We eventually reach the bottom of the vast subterranean cave and stand on a small wooden platform floating above a crystal-clear lake the size of a football field.

Once our eyes adjust to the little light penetrating from the thin shaft, we begin to notice beautiful stalagmites and stalactites decorating the walls of the cave formed drop by drop over millions of years. This is the pristine and isolated Abismo Anhumas, an eerily beautiful masterpiece of Mother Nature.

Soon we board the inflatable boat and tour the cavern by torchlight, while our guide explains to us all that is known about the Abismo Anhumas Abyss and points out special formations such as a curtain of folded limestone, massive chandeliers of rock, and monoliths sparking the imagination.

Eventually, the time has come to change quickly into wetsuits and peer down the world’s some of the biggest cave stalagmites growing from the cave floor, reaching up to 19.5 meters high. Snorkeling among the submerged limestone cones in cold, crystal-clear water is like visiting a different world.


The lake of Abismo Anhumas is approximately 80 meters deep with an average water temperature of 18°C. To compensate, it has a mesmerizing shade of emerald. It’s possible to scuba dive in the lake too, but that adds to the already steep price (~ $300 USD as of 2019). Having dived in Mexico’s cenotes, I believe I’m a tad bit too spoiled. So, I pass up diving this time.

An anteater skeleton lies where it died, stumbling over the hole’s edge 100 meters up

Back onto the floating deck, we prepare for the great ascent out of the cave one by one. In the past, participants had to rappel back to the surface by their own power, a hard workout that could take up to 30 minutes.

Now they no longer let you climb but pull you up through a system in less than 5 minutes. I have to say that the pull-up system was not smooth at all. I was worried at least three times as to why they stopped pulling me up. For me to enjoy the view? Not really…I figured out the reason when I put my feet back on solid ground. If you are curious, watch this video. Nevertheless, the man-powered system from 2019 may now be history. I heard that an electric pull-up system was installed recently in Abismo Anhumas.

Up and out, back in the daylight in one piece, it feels like the ones that have emerged from this very cave are the only survivors of an apocalypse.