The Cathedral, Efate

Diving into a deep underwater tunnel may generate feelings of faith in a higher power in certain people. The Cathedral at Efate, on the other hand, is said to receive its name from the shafts of light that penetrate through the surface and create strange dappled effects on the cavern's walls.

"The Cathedral is a remarkable towering narrow tunnel located around a 20-minute boat ride from Port Vila," Dickson-Smith says. "The cavern's entrance is tall and wide, about 22m (72ft) deep at the sandy bottom, and it narrows as you approach the "pulpit" at the apex." Beyond the pulpit is a short chimney that goes to the surface, where you can pop up and wave to the boat before swimming back down and out of The Cathedral to inspect the coral on the reef wall outside."

Many different fish species live on the reef, and if divers go close enough, animals like nudibranchs and leaf scorpionfish can be found concealed amid the coral.

Location: Efate Island, Vanuatu