Sue Daly / Port du Moulin, a natural rock arch, Sark, Channel Isles, UK, 2009

Tim Fitzharris / Natural bridge on El Matador State Beach, California

Tim Fitzharris / Natural bridge on El Matador State Beach, California

Konrad Wothe / Rock formations, Tassili of Maridet, Libyan Desert, Libya

Konrad Wothe / Rock formations, Tassili of Maridet, Libyan Desert, Libya

Steven Kazlowski / The North Window, natural sandstone rock arch in Arches National Park, Utah, USA. February 2009.

Angelo Gandolfi / Natural rock arch, Cares Gorge, Picos de Europa National Park, Cantabria, Spain. July 2008.

Angelo Gandolfi / Griffon Vultures (Gyps fulvus) flying over natural rock arch, El Castillo rocks, Canyon del Ebro and Rudron, Castilla y Leon, Spain.

Angelo Gandolfi / Natural rock arch at El Castillo rocks, Canyon del Ebro y Rudron, Castilla y Leon, Spain.

Wild Wonders of Europe / Muñoz / Natural arch, Great Bernera, Lewis, Outer Hebrides, Scotland, UK, June 2009.

Wild Wonders of Europe / Muñoz / Campaigh, a natural arch, Great Bernera, Lewis, Outer Hebrides, Scotland, UK, June 2009

Scott Leslie / Sea arch, The Arches Provincial Park, Newfoundland, Canada

Ingo Arndt / Natural rock bridge of eroded limestone, Palau

Yva Momatiuk & John Eastcott / Natural bridge and sandstone hoodoos, Bryce Canyon National Park, Utah

Flip Nicklin / Iceberg with a natural arch, Antarctic Peninsula, Antarctica

Philippe Clement / Manne Porte at sunset, a natural arch in the chalk cliffs at Etretat, Normandy, France

Philippe Clement / L'Aiguille and The Porte D'Aval at sunset, a natural arch in the chalk cliffs at Etretat, Normandy, France

Pete Oxford / Eroded volcanic tufa arch known as Darwin Arch, Darwin Island, Galapagos Islands, Ecuador

Jouan & Rius / The Island Archway, Campbell National Park, Victoria, Australia.

Jouan & Rius / The Island Archway, Campbell National Park, Victoria, Australia.

Konrad Wothe / Natural arch at Rialto Beach, Olympic National Park, Washington

Michael & Patricia Fogden / Natural arch at Spitzkoppe, Damaraland, Namib Desert, Namibia

Kevin Schafer / Cliffs with natural arch called Porte d'Aval and seastack, Etretat, Normandy, France

Gary K. Smith / Natural rock arch leading to Reynards Cave, Dovedale, Peak District NP, Derbyshire, UK,

Peter Lewis / Durdle Door natural rock archway, Dorset, UK. Jurassic Coast World Heritage Site.

Juergen Freund / Nature's Window - a natural rock arch, Kalbarri National Park, Western Australia

Juergen Freund / Nature's Window - a natural rock arch that overlooks the Murchison River in the Kalbarri National Park, Western Australia

Jack Dykinga / Escalante natural stone bridge with Box elder in foreground {Acer negundo}, Grand Staircase-Escalante, Utah, USA

Doug Perrine / Natural rock arch caused by wave erosion, Aruba, Caribbean

Jose B. Ruiz / Natural arch at sunset, Tabaibarril coast, Tenerife, Canary Islands

Pete Oxford / Natural rock arch in surf, Natural Bridges State Park, Santa Cruz, California, USA

Gavin Hellier / Tourists at North Window, Arches NP, Utah, USA

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Kevin Schafer / Seastack seen through Hole-in-the-Wall natural arch, Rialto Beach, Olympic National Park, Washington

Kevin Schafer / Seastack seen through Hole-in-the-Wall natural arch, Rialto Beach, Olympic National Park, Washington

Colin Monteath / Tunnel Beach showing natural arch, Otago Peninsula

Matthias Breiter / Iceberg, Gonzalez Videla Antarctic Base, Paradise Bay, Antarctic Peninsula, Antarctica

Matthias Breiter / Natural arch in iceberg, Gerlache Strait, Antarctic Peninsula, Antarctica

Hiroya Minakuchi / Natural arch in desert, Kalbarri National Park, Western Australia, Australia

Tom Vezo / Devil's Bridge, Sedona, Arizona

Onne van der Wal / Man exploring a natural arch in weathered icebergs off a glacier in Alaska. 2001

Onne van der Wal / The crew of yacht "Shaman" in the yacht's tender, heading through a natural arch in an iceberg, south coast of South Georgia.

Onne van der Wal / The crew of yacht "Shaman" in the yacht's tender, heading towards a natural arch in an iceberg, south coast of South Georgia. Model and Property Released.

Onne van der Wal / A yacht's tender taking a close-up look at a natural arch in an iceberg, south coast of South Georgia.

Onne van der Wal / The crew of yacht "Shaman" in the yacht's tender, heading towards a natural arch in an iceberg, south coast of South Georgia. Model and Property Released.

Onne van der Wal / The crew of yacht "Shaman" in the yacht's tender, heading towards a natural arch in an iceberg, south coast of South Georgia.

Roberto Rinaldi / Pietralunga with Lipari in the background, Aeolian islands, Italy.

Roberto Rinaldi / Pietralunga with Lipari in the background, Aeolian islands, Italy.

Norbert Wu / Natural arch, Rainbow Bridge National Monument, Arizona

Ingo Arndt / Turret Arch as seen through the North Window Arch at sunrise, Arches National Park, Utah

Kevin Schafer / Arches in offshore rock, Chiloe Island, Chile

Konrad Wothe / Rock formations, Tassili of Maridet, Libyan Desert, Libya

Ingo Arndt / Iceberg near Drygalski Fjord, South Georgia Island

Stephen Belcher / Wharariki Beach, Archway Islands, New Zealand

Stephen Belcher / Wharariki Beach, Archway Islands, New Zealand

Roberto Rinaldi / Carved iceberg with natural arch, Antarctic Peninsula.

Peter Lewis / Sun setting through the arch at Durdle Door, Jurassic Coast World Heritage Site, Dorset. November.

Peter Lewis / Sun setting through the arch at Durdle Door, Jurassic Coast World Heritage Site, Dorset. November.

Peter Lewis / Sun setting through arch at Durdle Door, Jurassic Coast World Heritage Site, Dorset. November.

Kevin Schafer / Cliffs with natural arch called Porte d'Aval and seastack, Etretat, Normandy, France

GEORGETTE DOUWMA / Natural bridge Bryce Canyon NP Utah USA. sandstone erosion

Jeff Foott / Delicate Arch, Arches National Park, Utah

Jeff Foott / Double Arch seen through Cove Arch, Arches National Park, Utah

Adrian Davies / River under natural stone arch in karst landscape, Rakov Skocjan, Notranjskiu Regijski Park, Slovenia. May, 2023.

Mike Read / View over Durdle Door, natural limestone arch, and beach. Lulworth Cove, Dorset, UK. September.

Nick Upton / Group of sea kayakers approaching a natural rock arch, exploring rugged coastline near Porthclais, St. David's, Pembrokeshire, Wales, UK. August, 2022.

Guy Edwardes / Blackchurch Rock, a natural arch stack, under stormy sky, Mountmill, Devon, England, UK. January, 2022.

Eric Baccega / Spitzkoppe's natural rock arch, a granite inselberg, Spitzkoppe mountain range, Namibia.

Orsolya Haarberg / Natural arch rock formation over a surging storm tide, Arnarstapi, Snaefellsnes peninsula, Iceland. February.

Graham Eaton / Natural arch in carboniferous limestone sea cliffs, Penmon, Anglesey, Wales, Irish Sea, UK. June, 2017.

Doug Gimesy / London Arch, formerly London Bridge, an offshore natural limestone arch formation, Port Campbell National Park, Victoria, Australia. June, 2015

Kirkendall-Spring / Kachina Bridge in Natural Bridges National Monument., USA. February.

Enrique Lopez-Tapia / Night sky over Stone arch, called the Julia arch. Ennedi Natural and Cultural Reserve, UNESCO World Heritage Site, Chad. September 2019.

Enrique Lopez-Tapia / Eroded sandstone arch arch, called the Julia arch, in the Sahara Desert, Ennedi Natural and Cultural Reserve, UNESCO World Heritage Site, Chad. September 2019.

Enrique Lopez-Tapia / Eroded sandstone arch arch, called the Julia arch, in the Sahara Desert, Ennedi Natural and Cultural Reserve (World Heritage, UNESCO). September 2019.

Enrique Lopez-Tapia / Eroded sandstone arch arch, called the Julia arch, in the Sahara Desert, Ennedi Natural and Cultural Reserve, UNESCO World Heritage Site, Chad. September 2019.

Enrique Lopez-Tapia / Eroded sandstone arch arch, called the Julia arch, in the Sahara Desert, Ennedi Natural and Cultural Reserve, UNESCO World Heritage Site, Chad. September 2019.

Enrique Lopez-Tapia / Aloba arch - eroded sandstone rock formation in the Ennedi Natural And Cultural Reserve, UNESCO World Heritage Site, Sahara Desert, Chad. September 2019.

Enrique Lopez-Tapia / Elephant arch - eroded sandstone rock formation in the Ennedi Natural And Cultural Reserve, UNESCO World Heritage Site, Sahara Desert, Chad. September 2019.

Emanuele Biggi / A natural rock arch in the Spitzkoppe mountains, Namib desert, Namibia

Philippe Clement / Tre Cime di Lavaredo / Drei Zinnen, three distinctive mountain peaks in the Sexten Dolomites seen from WW1 cave shelter, South Tyrol, Italy, October 2019