Amblyrhynchus cristatus Marine Iguana
Marine Iguanas feed in the sea (on the algae growing on underwater offshore rocks), and are the only lizards in the world to do so. They live only in the Galápagos Islands. Charles Darwin was fascinated by them on the historic voyage of the Beagle, though he found them exceptionally ugly and called them "imps of darkness".

Seven subspecies are recognized by some authorities, but the types don't seem very well differentiated, and it seems pretty clear from genetic studies that there is quite a bit of gene flow among the purported subspecies.

Subspecies I've seen:
A. c. hassi
Santa Cruz Marine Iguana
A. c. mertensi
San Cristóbal Marine Iguana
A. c. nanus
Genovesa Marine Iguana
A. c. venustissimus
Española Marine Iguana
Amblyrhynchus cristatus hassi Santa Cruz Marine Iguana
North Seymour Island, Galápagos Islands, EcuadorApril 2, 1994
Santa Cruz Marine Iguana (Amblyrhynchus cristatus hassi)
What an amazing sight -- dozens of large sea-going lizards piled up on the beach rocks, oblivious to the people admiring them.
South Plaza Island, Galápagos Islands, EcuadorApril 29, 2012
Santa Cruz Marine Iguana (Amblyrhynchus cristatus hassi)
Marine Iguanas spend most of their time lying around on rocks to gather heat.
Mosquera Beach, Galápagos Islands, EcuadorApril 29, 2012
Santa Cruz Marine Iguana (Amblyrhynchus cristatus hassi)
Most of Mosquera Beach was covered by sand, which was in turn covered by sea lions. But in the center of the sand a small lava outcrop housed a pair of resident iguanas.
North Seymour Island, Galápagos Islands, EcuadorMay 2, 2012
Santa Cruz Marine Iguana (Amblyrhynchus cristatus hassi)
When lying around on rocks doesn't gather enough heat, one can always try sitting up high.
Post Office Bay, Floreana Island, Galápagos Islands, EcuadorMay 3, 2012
Santa Cruz Marine Iguana (Amblyrhynchus cristatus hassi)
The marine iguanas on Floreana had more red coloration than any others we saw on this trip. Our guide told us that we were a little late in the year to see them in their full breeding color glory though.
Amblyrhynchus cristatus mertensi San Cristóbal Marine Iguana
Sombrero Chino Islet, Galápagos Islands, EcuadorApril 30, 2012
San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi) San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi)
Iguanas were basking up a storm on a sunny morning on the tiny spatter cone island Sombrero Chino.
James Bay, Santiago Island, Galápagos Islands, EcuadorApril 30, 2012
San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi) San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi) San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi) San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi) San Cristóbal Marine Iguana (Amblyrhynchus cristatus mertensi)
That afternoon the weather turned on-and-off drizzly, and when we visited a large colony of marine iguanas on the shore of James Bay, we found that many of them were huddled in crevices and beneath rock overhangs to avoid losing too much of their precious body heat. A brave few were splayed about in the open, and an even braver few were out in the ocean, returning from algae-munching expeditions.
Amblyrhynchus cristatus nanus Genovesa Marine Iguana
Darwin's Bay Beach, Genovesa Island, Galápagos Islands, EcuadorMay 1, 2012
Genovesa Marine Iguana (Amblyrhynchus cristatus nanus) Genovesa Marine Iguana (Amblyrhynchus cristatus nanus)
Genovesa is small and isolated from the other islands. The marine iguanas on this island are the smallest ones in the archipelago.
Amblyrhynchus cristatus venustissimus Española Marine Iguana
Punta Suarez, Española Island, Galápagos Islands, EcuadorMarch 29, 1994
Española Marine Iguana (Amblyrhynchus cristatus venustissimus)
Like many of the animals on the Galápagos, the marine iguanas are completely unafraid of people, so you can get decent pictures of them even with the lousy camera I had back then.
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