An octopus floats in the Mayotte Lagoon in the Indian Ocean on May 7, 2016. During spring low tides, there is very little water on the flats, even as little as 12 inches. Photographer Gabriel Barathieu used a wide-angle lens to capture this image.
Kukulkan Cenote on Mexico's Yucatan Peninsula forms part of the Chac Mool system and is noted for the spectacular light effects as the sun penetrates the darkness, in this image captured on March 12, 2016.
An oceanic whitetip shark swims in the Red Sea on Nov. 4, 2016. These animals are mostly solitary and are primarily found in open oceans.
A pod of orcas swim toward the setting sun in Tromso, Norway on Nov. 11, 2016.
A lion's mane jellyfish rises from the bloom towards the surface near Valdez, Alaska on July 12, 2016. Photographer Ron Watkins came across a dense bloom of moon jellyfish which ranged in depth from 6.5 feet to over 65 feet.
A larvae mantis shrimp uses its raptorial appendages to hunt on May 23, 2016. Photographer So Yat Wai took this shot during a blackwater dive in Anilao in the Philippines.
The wreck of the Louilla rests on top of Gordon reef on the edge of Egypt's Sinai Peninsula on Aug. 6, 2016. Wrecks become part of the eco-system as soft corals develop and can become shelter for schools of juvenile fish, but they can also have a devastating effect on their surroundings as they slowly deteriorate.
Three clownfish poke out of an anemone in Lambeh, Indonesia on Dec. 2, 2016. Clownfish and anemones enjoy a symbiotic relationship, as do parasitic isopods and clownfish. Isopods like to hang out in the mouths of clownfish and perhaps because of this, clownfish often open their mouths.
A batfish seperates from the school of fish in Shark Rafeen, Rash Mohamed National Park in Egypt on Aug. 22, 2016.
A whip coral goby rests on wire coral in Mozambique on Feb. 4, 2016. This image was captured with the Inon compact bug-eye lens, giving a lot of character to the goby's eye.
Two orcas swim in the North Sea off the coast of Yell, Scotland on Sept. 7, 2016. Photographer Melvin Redeker hoped to capture the iconic killer whales to draw attention to the North Sea's many ecosystems and habitats.
A cuttlefish (sepia officinalis) is posed to ward off danger, in Drawna Rocks, Porthkerris, England on July 31, 2016.
Cuttlefish will often make this type of threat display and only retreat once it's clear that the diving photographer or other recipient has not been intimidated. In some former hotspots for these fish, increased use of cuttlefish traps, especially during the mating season, has had a devastating impact on the population's numbers.
A firework anemone (pachycerianthus multiplicatus) sits deep in the ocean at Loch Duich, Scotland on Aug. 15, 2015. These anemones are found in deep and dark water, with the best subjects being around 82 feet or more.