Charles Darwin described the Galápagos land iguanas he observed as "ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance.

"[12] The Galápagos land iguana is one of the largest lizards in the world,[13] growing to a length of 0.9 to 1.5 m (3–5 ft), with a body weight of up to 13 kg (29 lb), depending upon which island they are from.

[14][15] Being cold-blooded, they raise their body temperature by basking on volcanic rock or other dark-colored stones that naturally absorb the heat of the sun.

[4][16] Land iguanas are primarily herbivorous; however, some individuals have shown that they are opportunistic omnivores, supplementing their diet with invertebrates, such as centipedes or arachnids, and carrion.

[4] Because fresh water is scarce on the islands, the Galápagos land iguana obtains the bulk of its moisture from the prickly-pear cactus (Opuntia sp.

[4][14] During the rainy season, land iguanas will drink from temporary vernal pools and other accumulated sources of water, and feast on the blousy, yellow flowers of the perennial succulent genus Portulaca.

The two species remain mutually fertile in spite of being assigned to distinct genera, and they occasionally hybridize where their ranges overlap.

Beginning in the early 1990s, the Galápagos land iguana has been the subject of an active reintroduction campaign on Baltra Island.