Alex Mustard / 2020VISION / Grey seal (Halichoerus grypus) swimming amongst kelp, Farne Islands, Northumberland, England, UK, August. 2020VISION Book Plate. Did you know? The 1914 Grey Seal Protection Act ensured this species’ s...

Andy Rouse / Galapagos green turtle (Chelonia mydas agassisi) underwater portrait, being inquisitive, note algae growing on head and shell

David Hall / Split-level of Cormorants (Phalacrocorax sp.) standing on rocks with Sea lettuce (Ulva sp.) seen underwater, Hussar Bay, Nigei Island, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Split level of a Lion's mane Jellyfish (Cyanea capillata) and Feather-boa kelp (Egregia menziesii), Seven-tree Island, Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

Shane Gross / Galapagos green sea turtles (Chelonia mydas agassizii) feeding on seaweed growing on lava rocks off Isabela Island, Galapagos, Ecuador. December.

Shane Gross / Two grey triggerfish (Balistes capriscus) fight over a large piece of plastic floating at the surface among sargassum seaweed (Sargassum natans) in the Sargasso Sea, Atlantic Ocean.

Claudio Contreras / Californian sea lion (Zalophus californianus) swimming in Southern sea palm (Eisenia arborea) and Giant Kelp (Macrocystis pyrifera) forest, San Benitos Islands, Baja California Pacific Islands Biosphe...

Alex Mustard / Portrait of a male short snouted seahorse (Hippocampus hippocampus) in sea oak seaweed (Halidrys siliquosa). Devon, England, United Kingdom. British Isles. English Channel. North East Atlantic Ocean.

Nick Hawkins / Sugar kelp (Sacchinaria latissima) off Nova Scotia, Canada. September

SCOTLAND: The Big Picture / Kelp forest (Laminaria digitata) with small fish, Shetland, Scotland, UK, July.

Marie Read / Horned Puffin (Fratercula corniculata) flying over a pattern of kelp and sea foam, photographed from above, St. Paul, Pribilof Islands, Alaska, USA. July.

Shane Gross / Queen conch (Lobatus gigas) juvenile feeding on algae growing on Seagrass (Thalassia testudinum) blades. Eleuthera, Bahamas.

Theo Bosboom / Patterns of algae on a limestone rock with sand, White sands beach, Causeway coast, Northern Ireland. April 2016.

Franco Banfi / Sugar kelp (Saccharina latissima) and Sea anemones (Actiniaria) on rock near iceberg. Tasiilaq, East Greenland. April.

Franco Banfi / Sugar kelp (Saccharina latissima) near iceberg, view upwards to gap in sea ice. Tasiilaq, East Greenland. April.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) in water, Puerto Egas, Santiago Island, Galapagos

Guy Edwardes / Seaweed covered rocks with Gaada Stack in background, Foula, Shetland, Scotland, UK. August, 2016.

Claudio Contreras / Californian Sealion (Zalophus californianus) in kelp (Macrocystis pyrifera) forest, San Benito del Este Island, Baja California Peninsula Pacific Islands Biosphere Reserve, Baja California, Mexico, Ma...

Michel Roggo / Rangimairewhenua or Blue Lake, Nelson Lakes National Park, South Island, New Zealand, February 2013. Photographed for The Freshwater Project

Alex Mustard / RF - Female grey seal (Halichoerus grypus) hovering in gully of kelp (oarweed: laminaria: Laminaria hyperborea). Farne Islands, Northumberland, England, United Kingdom. British Isles. North Sea. (This...

SCOTLAND: The Big Picture / Grey seal (Halichoerus grypus) swimming over kelp forest, Shetland, Scotland, UK, August.

Alex Mustard / California sea lion (Zalophus californianus) resting in the canopy of a forest of giant kelp (Macrocystis pyrifera). Santa Barbara Island, Channel Islands. Los Angeles, California, United States of Am...

Roy Mangersnes / Marine iguana (Amblyrhynchus cristatus) feeding in deep water to find algae, off the coast of Fernandina island on Galapagos. April 2016. Much of the algae on coast and at shallower depths have been k...

Roy Mangersnes / Marine iguana (Amblyrhynchus cristatus) feeding in deep water to find algae, off the coast of Fernandina island on Galapagos. April 2016. Much of the algae on coast and at shallower depths have been k...

Roy Mangersnes / Marine iguanas (Amblyrhynchus cristatus) basking on rock next to skeleton of one which starved to death. Unusually warm El Nino waters have killed a lot of the algae which is the food for these iguana...

Roy Mangersnes / Coastal scene on Fernandina Island, with small group of Marine iguanas (Amblyrhynchus cristatus). Galapagos. April 2016. Normally there would be a much larger group but El Nino weather has killed off...

Roy Mangersnes / Dead Marine iguana (Amblyrhynchus cristatus) on the coastal rocks on Santiago Island, Galapagagos, April 2016. It probably died of starvation as much of the algae in the region have died off due to un...

Alex Mustard / Aggregation of Golden jellyfish (Mastigias sp.) in a marine lake in Palau, the golden colour of this species comes from symbiotic algae in its tissues. Jellyfish Lake, Eil Malk island, Rock Islands, P...

Alex Mustard / Young California sea lion (Zalophus californianus) playing in the canopy of a forest of Giant kelp (Macrocystis pyrifera). Santa Barbara Island, Channel Islands. California, USA. North East Pacific Oc...

Andres M. Dominguez / Dove's-foot crane's-bill leaf (Geranium molle) and algae in ice with air bubbles, Sierra de Grazalema Natural Park, southern Spain, February.

Jeff Vanuga / Ephydrid flies (Ephydra sp) that eat microscopic algae and survives during the winter in thermal pools. Biscut Basin, Yellowstone National Park, Wyoming, USA, January.

Solvin Zankl / Kelp forest (Laminaria hyperborea), Atlantic Ocean, North West Norway, March.

Solvin Zankl / Thongweed (Himanthalia elongata) edible plant sold as 'Sea Spaghetti' for human consumption. From Roscoff, France, April. Preserved specimen.

Sven Zacek / Pink algae in fresh snow on the coast of the Baltic Sea, Lahemaa National Park, Northern Estonia. December 2012.

Solvin Zankl / Tiny crab on Broad-toothed Gulfweed (Sargassum fluitans) Sargassum Community. Sargasso Sea, Bermuda

Alex Hyde / Chlorophyte or green alga (Volvox aureus) in pond water. UK. The larger spheres are approximately 0.5mm in diameter. Digital composite image.

Jurgen Freund / Detail of Giant kelp (Macrocystis pyrifera) gas-filled bladders (pneumatocysts) Vancouver Island, British Columbia, Vancouver Island, Canada.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) diving to feed on algae, Sombrero Chino Islet, Santiago Island, Galapagos, Ecuador, May.

Pascal Kobeh / Group of California sea lions (Zalophus californianus) in a kelp forest (Macrocystis pyrifera), California, USA. Pacific ocean.

Pascal Kobeh / Group of California sea lions (Zalophus californianus) swimming in kelp forest (Macrocystis pyrifera), California, USA. Pacific ocean.

SINCLAIR STAMMERS / Timelapse of filaments of Oscillatoria, a type of Blue green algae gliding over each other, filmed using differential interference contrast.

Sue Daly / Furbelows seaweed (Saccorhiza polyschides), with fronds moving in the current, Sark, British Channel Islands, UK, June.

Brandon Cole / Red Sea Urchins (Stronglyocentrotus franciscanus) and Purple Sea Urchins (Stronglyocentrotus purpuratus) feeding on bottom algae and Giant kelp (Macrocystis pyrifera), Channel Islands National Marine...

Tom Gilks / Zanzibari woman at low tide with harvested seaweed (eucheuma spinosum) Matemwe, Zanzibar, Tanzania

Adam Burton,Adam Burton / Rockpools on the shores of Gjogv on Eysturoy, looking towards the mountainous island of Kalsoy. Faroe Islands. June 2012.

Claudio Contreras,Claudio Contreras / Man unloading seaweed, Hambungan Island, Danajon Bank, Central Visayas, Philippines, April 2013

Claudio Contreras,Claudio Contreras / Seaweed farm, near Taglibas, Danajon Bank, Central Visayas, Philippines, April

Alex Mustard / A diver explores Nikulasargj Canyona deep fault filled with fresh water in the rift valley between the Eurasian and American tectonic plates at Thingvellir National Park, Iceland. May 2011. In this ph...