Tsingy de Bemaraha is pretty fascinating thing.
Wikipedia:
"In several regions on western Madagascar, centering on this National Park and adjacent Nature Reserve, the superposition of vertical and horizontal erosion patterns has created dramatic "forests" of limestone needles.
The incredibly sharp limestone formations can cut through equipment and flesh easily, which makes traversing them extremely difficult."
Cracked.com
"Biologists call the area a bio-fortress. The park is so impassable and uncharted, in fact, that every time a team goes on an expedition there, they find approximately five new species.
Those limestone things really are razor-sharp. "Tsingy" is actually the Malagasy word for "where you cannot walk barefoot." When one expedition visited, they couldn't navigate with ordinary rock-climbing gear because (and these are actual quotes from an actual scientist) "Tsingy chewed equipment and flesh with equal ease. At times it was like climbing amid giant skewers, the consequences of a fall suggested in the mutilated trunks of toppled trees below."
And just in case you still think we're exaggerating, here's how Steven Goodman (the quoted scientist above) ended his trip: He and his team were walking on a normal, plain, flat path, when he turned his ankle just a little bit and stumbled. That's all -- he didn't even fall all the way; just took a brief knee. It took them two days to hobble back to a hospital to remove the limestone spike from his kneecap."