Nisyros volcano, high angle view, Nisyros Island, Dodecanese Islands, Greek Islands, Greece, Europe

December 3, 2012 - Colourful crater lakes of Kelimutu volcano, Flores Island, Indonesia. Tiwu Nua Muri Kofah (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched Lake). The two lakes are highly acidic due to underwater fumarole activity and are turqoise in colour.

December 3, 2012 - Colourful crater lakes of Kelimutu volcano, Flores Island, Indonesia. A crater wall separates Tiwu Nua Muri Koo Fai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched Lake). The two lakes are highly acidic due to underwater fumarole activity and are turqoise in colour.

December 3, 2012 - Colourful crater lakes of Kelimutu volcano, Flores Island, Indonesia. Tiwu Nua Muri Koo Fai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched Lake). The two lakes are highly acidic due to underwater fumarole activity and are turqoise in colour.

A view of the boiling mud at Namafjall, Iceland

Lesser masked weaver (Ploceus intermedius), Ngorongoro Crater, Tanzania, East Africa, Africa

Grey crowned crane (Southern crowned crane) (Balearica regulorum), Ngorongoro Crater, Tanzania, East Africa, Africa

Malachite Kingfisher, Ngorongoro Crater, Tanzania, East Africa

Colorful pink sky above the red volcano crater cone of Mount Fuji over Lake Kawaguchiko water on a summer morning sunrise in Japan. Vertical

Fiery colorful sky above the red crater cone of Mount Fuji at dawn sunrise over Lake Kawaguchiko water on a summer morning in Japan

Aerial view, crater lake with coloured rivers, near Skyggnisvatn, Iceland, Europe

Aerial view, volcano, crater rim with yellow sulphur, near Frioland ao Fjallabaki, Iceland, Europe

Aerial view, volcanic crater with colourful sulphur deposits, near Frioland ao Fjallabaki, Iceland, Europe

Hot spring, Yellowstone national park, Wyoming, USA

Aerial colorful sandstone in the Ramon crater in the Central Negev desert, Israel

A Pearly Soldierfish (Myripristis kuntee) that was photographed under water while scuba diving at Molokini Crater which is located offshore of Maui; Molokini Crater, Maui, Hawaii, United States of America

Ridgeback Slipper Lobster (Scyllarides haanii) hiding in its lair between lava rocks on Molokini Crater's backwall offshore of Maui; Molokini Crater, Maui, Hawaii, United States of America

Surrounded by patches of Rice Coral (Montipora capitata), a Red Slate Pencil Urchin (Heterocentrotus mamillatus) and a Needle-spined (Urchin Echinostrephus aciculatus) rest on Molokini Backwall which is located offshore of Maui, Hawaii, USA; Molokini Crater, Maui, Hawaii, United States of America

Hawaii, Big Island, Hawaii Volcanoes National Park, Kilauea Volcano, Puu Oo Crater fountaining

Hawaii, Oahu, Waikiki, Hula dancer playing ukulele along beach - close-up of midriff, Diamond Head in the distance.

Hawaii, Maui, Haleakala National Park, Haleakala Crater.

Hawaii, Big Island, Hawaii Volcanoes National Park, Kilauea, Pu'u O'o eruption, close-up fountaining action

Hawaii, Big Island, Hawaii Volcanoes National Park, Pu'u O'o vent, lava fountaining

Hawaii, Big Island, Hawaii Volcanoes National Park, Kilauea, Pu'u O'o eruption, fountaining action

Hawaii, Oahu, Coastline aerial of Kahala homes and Diamond Head Crater, Waikiki hotels background

Hawaii, Oahu, Waikiki, Outrigger canoes on the beach with a rainbow and Diamond Head in the background.

Hawaii, Big Island, Hawaii Volcanoes National Park, Lava action meeting sea

Hawaii, Maui, Molokini Crater, Reef scene with BlueStripe Snapper and Raccoon Butterflyfish.

Hawaii, Oahu, Aerial of Diamond Head Crater with coastline view, Kahala homes foreground and Waikiki hotels background

Hawaii, Maui, Silver sword on Haleakala Crater blooming, view overlooking clouds

Hawaii, Big Island, Hawaii Volcanoes National Park, Fountaining Lava, Puu Oo Vent,

Hawaii, Maui, Molokini, crater aerial,

Hawaii, Maui, Molokini Crater, aerial view.

Hawaii, Maui, Haleakala National Park, Haleakala Crater.