Alex Mustard / Schools of fish, including Bohar snappers (Lutjanus bohar), Yellow-spotted trevally (Carangoides orthogrammus) and Bigeye trevally (Caranx sexfasciatus) gathering adjacent to a colourful coral reef wi...

Alex Mustard / Three Fordson WOT 3 trucks (illuminated by off-camera strobes), surrounded by Red Sea soldierfish (Myripristis murdjan) on the lower level of Hold 2 of the wreck of the SS Thistlegorm. Sha'ab Ali...

Alex Mustard / Two Red Sea goatfish (Parupeneus forsskali) wrapping their barbels around each other, fighting, Sharm El Shiekh, Sinai, Egypt. Red Sea.

Alex Mustard / Looking down at the top of a submerged reef covered in corals (Acropora spp. and Pocillopora sp.), Fathers Reef, Lolobau Island, Papua New Guinea. Bismark Sea, Pacific Ocean.

Alex Mustard / Orange painted frogfish (Antennarius pictus) resting between the venemous spines of a Fire urchin (Asthenosoma varium), Batangas marine protected area, Luzon, Philippines. Verde Island Passages, Pacif...

Alex Mustard / Coleman shrimps (Periclimenes colemani) pair, female on right, camouflaged in their Fire urchin (Asthenosoma varium) home, Batangas marine protected area, Luzon, Philippines. Verde Island Passages, Pa...

Alex Mustard / Saddleback anemonefish (Amphiprion polymnus) and a Spotted porcelain crab (Neopetrolisthes maculatus) living together in an anemone. Bitung, North Sulawesi, Indonesia, Lembeh Strait, Molucca Sea.

Alex Mustard / Pygmy seahorse (Hippocampus bargibanti) among a Sea fan (Muricella sp.) on a coral reef, Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Marine iguana (Amblyrhynchus cristatus) feeding on green algae on seabed, with more iguanas on the surface behind, Cape Douglas, Fernandina Island, Galapagos Islands, Pacific Ocean.

Alex Mustard / Three Stingrays (Dasyatis americana) swimming over sand in shallow water, The Sandbar, Grand Cayman, Cayman Islands, Caribbean Sea.

Alex Mustard / Two divers exploring the bow of the USS Kittiwake wreck (a US Military submarine rescue vessel deliberately sunk as a diving attraction in 2011), Seven Mile Beach, Grand Cayman, Cayman Islands, Caribb...

David Perpinan / Flathead grey mullet (Mugil cephalus) and Salema (Sarpa salpa) school swimming past the camera in the mouth of the Besos river. The fish enter and leave frame. Barcelona, Spain. October.