Jellyfish Lake (Palauan: Ongeim'l Tketau, “Fifth Lake”) is a marine lake located on Eil Malk island in Palau. Eil Malk is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror and Peleliu. There are about 70 other marine lakes located throughout the Rock Islands. Jellyfish Lake is one of Palau's most famous dive (snorkeling only) sites. It is notable for the millions of golden jellyfish which migrate horizontally across the lake daily.

A competitor prepares to snorkle during the World Bog Snorkelling Championships on August 28, 2011 in Llanwrtyd Wells, Wales. In 2012, following the Olympic Games, Llanwrtyd Wells will host the inaugural World Alternative Games. (Photo by Harry Engels/Getty Images)

It looks like an underwater tornado, but a diver was actually stuck in the middle of a huge school of fish. The fish swarmed around Mika Woyda in their thousands as she swam off the coast of Cabo Pulmo, Mexico. Her husband Caine Delacy snapped the breath-taking images of Mika in scenes he revealed he had never witnessed in 20 years of diving. Before entering the water the couple, who live in Boulder, Colorado, had some shots in mind but never imagined what they would capture. Here: photographer Caine Delacy with his wife Mika Woyda. (Photo by Caine Delacy/Mika Woyda/Caters News)

Zoee Heath of New South Wales competes in the womens U18 discus throw during day two of the Australian Junior Athletics Championships at Sydney Olympic Park Athletic Centre on March 11, 2011 in Sydney, Australia.

South Korean girl group KARA arrive during the 21st High1 Seoul Music Awards at Olympic gymnasium on January 19, 2012 in Seoul, South Korea. (Photo by Chung Sung-Jun/Getty Images)

O Santa Claus of Australia competes in the mens 80–84 years 100 metres heats during day two of the 2009 Sydney World Masters Games at Sydney Olympic Park on October 11, 2009 in Sydney, Australia. (Photo by Mark Nolan/Getty Images)

Californian photographer and conservationist Octavio Aburto had spent years photographing the school in Cabo Pulmo National Park, Mexico – and had been trying to capture this exact shot for three years. “Together with my friend David Castro, we were diving with a large group of Bigeye travellies at Cabo Pulmo National Park, Mexico. Thousands of fish forming a ball during the reproduction courtship. In the afternoon, these fish congregate to form a large spawning aggregation around the reefs of the National Park”. (Photo and caption by Octavio Aburto)

“Alice in Waterland” is a beautiful series of photographs re-imagining the Lewis Carroll classic underwater. It’s a creation of photographer Elena Kalis, who lives on a small island in The Bahamas, surrounded, she says, “by pristine clear warm water. Underwater is where I spend a lot of time; snorkeling, diving, photographing. It is fascinating how the world changes down below: light, sound, gravity and proportions are different from what we are used to”. (Photo by Elena Kalis)