The massif runs about 150 kilometers from north-northeast to south-southwest and stretches up to 50 kilometers wide, rising to around 1,000 meters. Its bedrock is the Makay Formation - Triassic-and-Jurassic sandstones and mudstones, a cousin of the rock that built nearby Isalo - and like Isalo it has been sliced by erosion into something fantastical. But where Isalo opens into broad canyons, the Makay coils tighter, its sinuous gorges branching and rebranching until the topography itself becomes a wall. This is why the place is what it is: the deeply dissected terrain makes the interior all but impassable on foot, sealing off the canyon floors from the outside world for ages. The massif also serves as a watershed, with rivers like the Sakeny and the headwaters of the Mangoky, Morondava, and Maharivo rising from its slopes and running off toward the Tsiribihina or the Mozambique Channel.

The contrast between ridge and ravine is stark. Up on the exposed plateaus, vegetation is thin and tough - drought-hardened plants of the Didiereaceae and spurge families clinging to shallow soil, with only scattered patches of dry forest. Drop into the canyons and the world flips: lush gallery forest, stands of bamboo, screwpine, and riverine palms thriving in the shelter and moisture the gorges trap. That sheltered green is what makes the Makay biologically precious. Its native lemurs include the white Verreaux's sifaka, the ring-tailed lemur, and several nocturnal mouse and dwarf lemurs, while the canyons also shelter the fossa - the puma-like predator that is Madagascar's largest native carnivore, a creature found nowhere else on Earth, prowling a fortress of stone.

The Makay's reputation rests on what keeps turning up in it. Because the canyon floors have been so isolated for so long, they hold biotopes sheltered from human reach, and scientific expeditions into the massif have repeatedly documented species new to science. French explorer Evrard Wendenbaum became its great champion, leading expeditions that brought the Makay to international attention and pushed for its protection. A landmark 2010 expedition into the labyrinth produced a 3D documentary, "Makay, Adventurers of the Lost World," that carried images of these hidden canyons to audiences who had never heard the name. The term "lost world" is usually marketing hyperbole. For the Makay, it is close to a literal description of a place still giving up its secrets.

Few people live in the Makay, and almost no one in its heart. The terrain that locks out scientists locks out settlement too; the massif is largely uninhabited, with residents clustered in small villages of 500 or fewer along its edges. They herd zebu, the humped cattle central to Malagasy life, and draw on the massif's forests for what they need. Reaching the place is itself an undertaking - the road toward Beroroha at the southern flank is unpaved National Road 15, passable only by 4x4. This inaccessibility has been the Makay's great protector, holding deforestation and development at bay where they have hollowed out so much of Madagascar. But isolation is a fragile shield, and the work of formally safeguarding this labyrinth - this last lost world - has only recently begun.