These are the breathtaking pictures of the world's largest stone forest - made up of hundreds of razor sharp vertical rocks.
The colossal 600km square landscape is a labyrinth of 300ft high spiked towers, slot canyons and caves.
But despite its harrowing appearance and dangerous structure, the bizarre space is in fact home to a whole host of animals.
In a remote part of Madagascar the spectacular structure is known as the Tsingy, which translates as 'where one cannot walk'.
It is formed by tropical rain which eroded the limestone into razor sharp pinnacles.
The Tsingy, or stone forest as it is more commonly known, is the largest of its kind in the world.
But with it's narrow passageways, knife-edged towers and remote location the stone forest has remained largely unexplored.
Intrepid explorer and photographer Stephen Alvarez is just one of a handful of people lucky enough to capture the natural phenomena on camera.
The 47-year-old visited the Tsingy de Bemaraha national park, home of the stone forest, with a team of explorers as part of an expedition for National Geographic Magazine.
The photographer from Tennessee squeezed through tiny passageways and clambered over rocks which he said were so sharp they cut his skin and tore the soles of his shoes.
He said: "I'd never seen a landscape like it. "My first impression was thank god, it was more tremendous than I had ever imagined and I knew straight away I would be able to get some fantastic photos.
"It is in such a remote part of Madagascar, that no-one has ever spent a long time there and there have been very few images ever published of it.
Stephen said the Tsingy was so remote it took him five days to reach it from Madagascar's capital and it was so difficult to explore it took a whole day to walk just half a mile.
"It's like a cave without a roof, it gets a tremendous amount of tropical rain that has eroded the rock into these sharp rock pinnacles.
"The rocks themselves are really sharp, they stick up like giant steak knives. It is one of the most difficult places I've ever explored."
But he said despite the dangerous and inhospitable environment, the Stone forest home to a whole host of animals from white-legged lemurs to lizards.
Stephen added: "There's forest within those rocks and animals including families of lemurs live within it.
"It's an unbelievable experience to watch them, they forage in the forest in the day and jump like acrobats from the sharp pinnacles where they sit at night.
"The stone forest is a natural phenomena and is largest one of it's kind in the world.
"Everyday I felt lucky to be there, lucky that I was spending time in such a spectacular place that most people will never get the chance to see.
"It is certainly the most unusual landscape I've ever seen, it's the only one that had to be seen to be believed."Suggest a correction