Sacred Cenote, Mayan ruins, Chichen Itza, UNESCO World Heritage Site, Yucatan, Mexico, North America

The gigantic Gruta de Benagil sea cave (Benagil Cathedral), Algarve, Portugal

Cave of Poetry (Grotta della Poesia), Roca Vecchia, Lecce, Salento, Apulia, Italy

The illuminated interior of Paradise Cave in Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

The illuminated interior of Paradise Cave in Phong Nha Ke Bang National Park, Quang Binh, Vietnam, Indochina, Southeast Asia, Asia

Scuba Diver inside Cave, Pseudanthias squamipinnis, Paradise Reef, Red Sea, Egypt

Scuba Diver inside Cave, Paradise Reef, Red Sea, Egypt

Scuba Diver inside Cave, Paradise Reef, Red Sea, Egypt

Scuba Diver inside Cave, Pseudanthias squamipinnis, Paradise Reef, Red Sea, Egypt

Scuba Diver inside Cave, Paradise Reef, Red Sea, Egypt

Cave of Papafragas, Milos, Cyclades, Greek Islands, Greece

Southern coast, sea and rock formations, Kleftiko, Milos Island, Cyclades Islands, Greek Islands, Greece, Europe

Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

Colourful Paradise cave, Phong Nha-Ke Bang National Park, UNESCO World Heritage Site, Vietnam, Indochina, Southeast Asia, Asia

Split image of lush vegetation and free diver observing lettuce coral, Turbinaria reniformis, next to cave entrance, Palau, Micronesia.

Whitetip reef shark, Triaenodon obesus, resting in cave, Namu atoll, Marshall Islands (N. Pacific).

Swimming at Cenote Ik Kil in Yucatan, Mexico, a natural pit, or sinkhole near Chichen Itza. Yucatan Peninsula, Quintana Roo, Mexico. Ik Kil was sacred to the Mayans who used this cenote for both relaxation and ritual services centuries ago.

Cenote Ik Kil in Yucatan, Mexico, a natural pit, or sinkhole near Chichen Itza. Yucatan Peninsula, Quintana Roo, Mexico. Ik Kil was sacred to the Mayans who used this cenote for both relaxation and ritual services centuries ago.

Gran Cenote de Tulum in Yucatan Peninsula, Quintana Roo, Mexico. There are thousands of cenotes dotted all over Mexico���s Yucatan Peninsula, and their existence is as much a defining characteristic of the region as is the distinct geological feature from which they result. Once revered by the ancient Mayans as sacred wells, they are now magnets for tourists, adventurers, and explorers alike.

Mystical cave in Formentera, Spain

Icecave Dobsinska at the National Park Slovak Paradise, Slovakia, Europe

A cave entering the water from the beach at Praia da Coelha, Algarve, Albufeira. Portugal

Sitting on the paradise beach of Kroreza or Krorez in a cave on the Albanian riviera in Sarande, Albania, Europe

A natural summer beach cave at Praia da Coelha, Algarve, Albufeira. Portugal

Kalalau Beach, viewed from a cave, Na Pali Coast State Park; Kauai, Hawaii, United States of America