Africa’s largest canyon, 160 km long and 550 m deep, with a five-day hike along its floor.
Sheer desert escarpment near Riyadh.
Otherworldly landscape of limestone chimneys.
Spectacular two-level limestone caves.
A "mini Grand Canyon" of red rock.
Windmills, spa towns and a meteor crater.
Karst caves stuffed with Buddhas amid sugarloaf mountains.
Eroded "moon landscape" near the coast.
One of the largest green canyons on Earth, seen from God’s Window and the Three Rondavels viewpoints.
Six sapphire lakes held by natural travertine dams in the Hindu Kush — Afghanistan’s first national park.
Wind-carved kalut ridges in one of the hottest places ever measured on Earth.
Eroded clay badlands a stone’s throw from the city.
Home of Son Doong, the world’s largest cave, plus Paradise Cave and boat trips into the river cave of Phong Nha itself.
Baltic island of rauk sea stacks and the Hanseatic walled town of Visby.
Sea cave on the Algarve coast with a round skylight in its domed roof — reached by boat, kayak or paddleboard.
Row through limestone karsts and rice paddies on the "Ha Long Bay on land", then climb to the Mua Cave viewpoint.
Limestone-cliff beach reachable only by longtail boat, and the best rock-climbing spot in Southeast Asia.
Monasteries atop soaring rock pillars.
Climb 740 steps up the El Penol monolith for views over a maze of turquoise reservoir lakes.
Rift-valley site of the world’s oldest parliament, where the tectonic plates pull apart.
Gunung Mulu’s vast cave system, including the Deer Cave and its nightly bat exodus.
Rainbow-striped Andean valley of adobe villages in Argentina’s far northwest.
England’s chalk-white front door: cliff-top paths above the Channel with France visible on a clear day.
Slot canyon on Navajo land near Page, Arizona, carved into swirling sandstone by flash floods.
See fossilized trees, painted desert badlands, ancient sites, and Triassic landscapes in Petrified Forest National Park.
See the steep dark cliffs and narrow river-carved gorge of Black Canyon of the Gunnison National Park.
Explore sandstone domes, cliffs, canyons, and the Waterpocket Fold in Capitol Reef National Park.
Descend into vast limestone caves and desert landscapes at Carlsbad Caverns National Park.
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