Alex Mustard / A diver explores Silfra Canyon, a deep fault filled with fresh water in the rift valley between the Eurasian and American tectonic plates at Thingvellir National Park, Iceland. May 2011. In this phot...

John Shaw / Shoreline of Lake Powell, seen from Alstrom Point on Romana Mesa. Glen Canyon National Recreation Area, on the Arizona/Utah border, USA, January.

Jack Dykinga / Rainbow over Long Canyon with fall coloured Cottonwood (Populus) trees against canyon walls, Burr Trail, Grand Staircase-Escalante National Monument, Utah, USA, October 2018.

Tim Fitzharris / Wildflowers and cacti, Caprock Canyons State Park, Texas

Oriol Alamany / Snow Leopard (Panthera uncia) female with two cubs climbing a canyon cliff at dusk at 4400 metres, Spiti valley, Cold Desert Biosphere Reserve, Himalaya mountains, Himachal Pradesh, India, February

Erlend Haarberg / Marble formations in alpine landscape. Lahko National Park, Fjell, Norway, July.

Guy Edwardes / Waterfall in Fjaorargljufur canyon, Kirkjubaejarklaustur, Iceland, August 2017.

Jack Dykinga / Toroweap Overlook in sunrise light illuminating rim rocks with Colorado River far below, Grand Canyon National Park, Arizona, USA.

Jack Dykinga / Banded Navajo Sandstone slot canyon in the Escalante Canyon complex. Grand Staircase-Escalante National Monument, Utah, USA.

Jack Dykinga / Indian paintbrush (Castilleja sp.) flowers amid boulders in a stream, in narrow canyon with conifers in background Grand Staircase-Escalante National Monument, Utah, USA.

Jack Dykinga / Cottonwood (Populus fremontii) trees forming a sinuous line of yellow trees at sunset, in Deer Creek Canyon, Grand Staircase-Escalante National Monument, Utah, USA

Jack Dykinga / Narrows with canyon wall reflections in mud patterned shore, Vermilion Cliffs National Monument, Paria Canyon Wilderness, Arizona, USA.