Jack Dykinga / Winter snow storms cause wind-blown drifting along the canyon rim, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Bryce Canyon National Park, Utah. Bristlecone pine clinging to the canyon rim at dawn, Bryce Canyon National Park, Utah, USA, January.

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

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

Jack Dykinga / Cap-rocks on the rim of the Escalante Canyon at dawn. Grand Staircase-Escalante National Monument, Utah, USA, October 2012.

David Pattyn / Temperate rainforest scenic with ancient Red cedar tree (Thuja plicata). Pacific Rim National Park, Vancouver Island, British Columbia, Canada, August.

Floris van Breugel / Colorful layers of rock on the inside of Mount St Helens' crater, seen from the rim. Washington, USA. May 2013

Jack Dykinga / North Rim at Cape Royal with sunset storm light streaming in rays, backlighting the canyon ridges, Grand Canyon National Park, Arizona, USA

Alex Mustard / Lionfish (Pterois volitans) sitting on the rim of large sponge on Bloody Bay Wall, Little Cayman, Cayman Islands, Caribbean Sea.

Ernie Janes / Northern pitcher plant (Sarracenia purpurea) with fly on rim

Matthew Maran / Waterfall on the the Darling River with a fallen tree as a bridge over the waters. West Coast Trail, Pacific Rim National Park Reserve, west coast of Vancouver Island, Canada, September 2010.

Matthew Maran / Surfer Benj Yougson at Long Beach. Pacific Rim National Park Reserve, west coast of Vancouver Island, Canada, September 2010. Model released

Matthew Maran / Driftwood on a beach with the coastline stretching to the horizon. Wickaninnish Beach, Pacific Rim National Park Reserve, West coast of Vancouver Island, Canada, September 2010.

Matthew Maran / Hikers crossing a thin footbridge over a river. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010, model released

Matthew Maran / Hikers building up a fire in their cliff-overhang cave. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September, Model released

Matthew Maran / A man sitting in the cable car of a chair bridge as it crosses a river. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010. Model released

Matthew Maran / A man looking out to sea by coastal rock stacks. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010. Model released.

Matthew Maran / Hikers talking as they warm themselves by a campfire on a beach. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010. Models released.

Matthew Maran / A hiker building a fire at his campsite. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010. Model released.

Matthew Maran / People in a small boat with the sun setting on the horizon. Pacific Rim National Park, Vancouver Island, Canada, September 2010, model released

Matthew Maran / Two people pausing on a woodland path. The West Coast Trail, Pacific Rim National Park, Vancouver Island, Canada, September 2010. Model released.

LYNN M. STONE / Portrait of Golden Retriever puppy with paw on rim of basket full of gourds, Connecticut, USA

Jack Dykinga / South rim of Moran Point at sunrise, with the Colorado River below, Grand Canyon National Park, Arizona, USA

Jack Dykinga / Pinyon pine (Pinus edulis) and Utah juniper (Juniperus osteosperma) on kaibab limestone spires in morning fog, North Rim, North Kalbab Trail, Grand Canyon National Park, Arizona, USA

Juan Carlos Munoz / View from the caldera rim of the Chico Volcano, Sierra Negra, Isabela Island, Galapagos, January 2009

Juan Carlos Munoz / Close up of foot of a hiker on the caldera rim of Los Gemelos, Santa Cruz Island, Galapagos, January 2009. Model released.

Fabio Liverani / Tree frog {Hyla sp} on rim of tropical fungus, Tambopata National Reserve, Amazonia, Peru

Igor Shpilenok / Looking down into the crater lake of the Maly Semyachik Volcano with ice at the rim and azure blue colouring caused by the acidic water, July.

Jack Dykinga / Snow covered Pinyon Pines (Pinus edulus) overlooking Shoshone Point at sunrise, East Rim, Grand Canyon NP, Arizona, USA

Jack Dykinga / North Kaibab Trail with Pinyon Pine (Pinus edulis) and Utah Juniper (Juniperus osteosperma), North Rim, Grand Canyon NP, Arizona, USA

Jack Dykinga / Snow covered Pinyon Pines (Pinus edulus) with pine cones, overlooking the West Rim, Grandview Point, Grand Canyon NP, Arizona, USA

Jack Dykinga / Moran point in the snow at sunrise, with the North Rim in the background, Grand Canyon NP, Arizona, USA

Jack Dykinga / Snow on Pinyon Pines (Pinus edulis) at sunrise, East Rim Drive, South Rim, Grand Canyon NP, Arizona, USA

Jack Dykinga / Snow covered Ponderosa Pine (Pinus ponderosa) branches with North Rim in the Background, Grand Canyon NP, Arizona, USA

Jack Dykinga / North Rim of Cape Royal at sunset, Grand Canyon NP, Arizona, USA

Jack Dykinga / North Rim of Cape Royal at sunrise, Grand Canyon NP, Arizona, USA

Jack Dykinga / Ponderosa Pine (Pinus ponderosa) pine cone and needles in the snow, South Rim, Grand Canyon NP, Arizona, USA

Jack Dykinga / Sunset at Yaki Point on the South Rim with stratified rim rocks and minute storm clouds inside the canyon below, Grand Canyon National Park, Arizona, USA.

Jack Dykinga / Rainbow after a storm over Mount Hayden, Point Imperial, North Rim, Grand Canyon National Park, Arizona, USA.

Jack Dykinga / Ponderosa pines {Pinus ponderosa}, Promontory Butte on General George Crook Trail along the Mogollon Rim, Apache Sitgreaves National Forest, Arizona, USA

Pete Oxford / Sulphur fulmerole in crater of active volcano, Sierra Negra, Isabela Is, Galapagos

Yva Momatiuk & John Eastcott / Coyote (Canis latrans) looking for handouts from tourists, Mather Point parking lot on South Rim, Grand Canyon National Park, Arizona

Tim Fitzharris / South Rim of Grand Canyon with a dusting of snow seen from Yaki Point, Grand Canyon National Park, Arizona

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) large male on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group wallowing in seasonal pool on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group wallowing in seasonal pond on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) old male in dry season on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Espen Bergersen / People walking along the rim of Hverfjall. Hverfjall is a tephra cone or tuff ring volcano in northern Iceland, to the east of Myvatn. Iceland, May 2016

Charlie Summers / Rock squirrel (Otospermophilus variegatus) on the rim of the Grand Canyon, Arizona, USA, September.

Jack Dykinga / Dead trees and smoke plume of forest fire in distance, fire started by lightning strike. Near North Rim of Grand Canyon National Park, Kaibab National Forest, Arizona, USA. 2019.

Steven David Miller / Kings Creek and sandstone cliffs, viewed from Kings Canyon Rim walk. Watarrka National Park, Northern Territory, Australia. 2014.

Jack Dykinga / Winter snow storms cause wind-blown drifting along the canyon rim, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Buff coloured sandstone spire at sunset, at the rim of Escalante and Calf Creek sandstone wilderness Grand Staircase-Escalante National Monument, Utah, USA, October 2018.

Marie Read / Red-winged blackbird (Agelaius phoeniceus) male calling and displaying, backlit, showing steamy breath on a chilly spring morning, Ithaca, New York, USA, April.

David Fleetham / View across crater of dormant Haleakala / East Maui Volcano. Haleakala National Park, Maui, Hawaii. March 2016.

Sandesh Kadur / Timelapse of clouds masking Ngorongoro Crater rim, Ngorongoro conservation area, Tanzania.

Jack Dykinga / Saddle Mountain overlook (Saddle Mountain at left) at dawn with water filled rim-rock in the foreground. Grand Canyon National Park, Arizona, USA.

Jack Dykinga / Snow-covered Limber pine (Pinus flexilis) on north facing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA. January 2018.

Jack Dykinga / Snow covered Limber pine (Pinus flexilis), on northfacing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA. January 2)18.

Jack Dykinga / Snow covered Limber pine (Pinus flexilis), on northfacing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA. January 2)18.

Jack Dykinga / Snow covered Limber pine (Pinus flexilis), on northfacing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA. January 2)18.

Jack Dykinga / Snow covered Limber pine (Pinus flexilis), on northfacing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA.

Jack Dykinga / Snow-covered Limber pine (Pinus flexilis) on north facing canyon rim, with the spires and pinnacles in the background. Bryce Canyon National Park, Utah, USA. January 2018.

Kirkendall-Spring / Snow plastered trees below the Watchman along the Rim Drive with Mount Scott in the distance, Crater Lake National Park. Oregon, USA. March 2018.

Kirkendall-Spring / Woman skiing past snow plastered trees below the Watchman along the Rim Drive in Crater Lake National Park. Oregon, USA. March 2018. Model released.

Kirkendall-Spring / Winter view of Crater Lake from the West Side of Rim Drive, Crater Lake National Park. Oregon, USA. March 2018.

Kirkendall-Spring / Woman cross country skiing along the north side of Rim Drive in Crater Lake National Park. Oregon, USA. Model released,

Kirkendall-Spring / Woman cross country skiing along the north side of Rim Drive in Crater Lake National Park, Oregon, USA. Model released.

Kirkendall-Spring / Woman cross country skiing along the north side of Rim Drive in Crater Lake National Park. Oregon, USA. March 2018. Model released.

Kirkendall-Spring / Woman cross country skiing along the north side of Rim Drive in Crater Lake National Park, Oregon, USA. March. Model released.

Kirkendall-Spring / Woman skiing around Crater Lake on the Rim Road near North Junction in Crater Lake National Park, Oregon, USA. March. Model released.

Kirkendall-Spring / Woman skiing around Crater Lake on the Rim Road near North Junction in Crater Lake National Park, Oregon, USA. March. Model released.

Vincent Grafhorst / Tourists on crater rim of active volcanic crater, Danakil Depression, Ethiopia

Bruno D'Amicis / Wild Apennine wolf (Canis lupus italicus) pup on a forest rim in summer. Central Apennines, Abruzzo, Italy. September. Italian endemic subspecies.

Bruno D'Amicis / Wild Apennine wolf (Canis lupus italicus) pup on a forest rim in summer. Central Apennines, Abruzzo, Italy. September. Italian endemic subspecies.

Frederique Olivier / Panning shot of Ngorongoro Crater from the crater rim, Tanzania.

Alex Hyde / The rim of Maliau Basin on the horizon, towering above the dense rainforest it encloses. Maliau Basin, Sabah, Borneo, May 2011.

Jiri Lochman / The rim of the ancient volcanic crater, Border Ranges National Park, Gondwana Rainforest UNESCO Natural World Heritage Site, New South Wales, Australia.

Jiri Lochman / Rim of ancient volcanic crater, Border Ranges National Park, Gondwana Rainforest UNESCO Natural World Heritage Site, New South Wales, Australia.

Graham Eaton / Grey heron (Ardea cinerea) standing at rim of infinity pool, Maldives, Indian Ocean, January 2017.

Inaki Relanzon / Grand Canyon's South Rim, Grand Canyon National Park, Arizona, USA, June 2012.

Jack Dykinga / Mount Hayden peak above mist, Grand Canyon. Taken from Point Imperial on the Canyon's North rim, Arizona, USA, September.

Jack Dykinga / Mount Hayden peak above fog, Grand Canyon. Taken from Point Imperial on the Canyon's North rim, Arizona, USA

Jack Dykinga / Mount Hayden above fog, Grand Canyon. Taken from Point Imperial on the Canyon's North rim, Arizona, USA. September.

Christophe Courteau / Panoramic view across the crater of Ol Doinyo Lengai, known locally as The Mountain of God, Rift Valley, Tanzania. It is still an active volcano.

Tim Fitzharris / Ponderosa Pine (Pinus ponderosa) trees, Mogollon Rim, Mazatzal Wilderness, Coconino National Forest, Arizona

Tim Fitzharris / Ponderosa Pine (Pinus ponderosa) trees, Mogollon Rim, Mazatzal Wilderness, Coconino National Forest, Arizona

Alex Hyde / (Eryngium carlinae) flowering next to the crater rim of Volcano Irazu, 3400 m. Costa Rica

Alex Hyde / (Eryngium carlinae) flowering next to the crater rim of Volcano Irazu, 3400m Costa Rica

Alex Hyde / Vegetaion including huge leaves of (Gunnera insignis) growing next to the crater rim of Volcano Irazu, 3400m Costa Rica

Alex Hyde / (Gaultheria myrsinoides) flowering next to the crater rim of Volcano Irazu, 3400m. Costa Rica

Alex Hyde / (Maianthemum gigas) flowering next to the crater rim of Volcano Irazu, 3400m, Costa Rica

Alex Hyde / Poor Man's umbrella (Gunnera insignis) growing around the caldera rim of Volcano Irazu, Costa Rica

Alex Hyde / (Castilleja irasuensis) flowering next to the crater rim of Volcano Irazu, 3400m. Costa Rica