A large lizard, they vary in length from 60 to 136 centimetres (24 to 54 in), and skin colours range from a steely grey to a dark green and even brown.

The rhinoceros iguana, like other members of the genus Cyclura, is a large-bodied, heavy-headed lizard with strong legs and a vertically flattened tail.

[6] Like all reptiles, rhinoceros iguanas are cold-blooded, meaning they need external sources to heat themselves; they move as the sun shifts in order to get an optimal internal temperature.

[9][10] Ranging in scattered locations throughout Hispaniola (in both Haiti and the Dominican Republic), populations are stable only on Isla Beata and the extreme of the Barahona Peninsula, inside Jaragua National Park.

Though not restricted to one single habitat, the iguanas are found most abundantly in scrub woodlands of the Hispaniolan dry forests (characterized by xeric, rocky terrain of eroded limestone with minimal flora), coastal terraces, lowlands of the mainland, plus several offshore islands and small cays, all with slightly different habitat types.

True to the name “rock” iguana, they favor rather barren landscapes with smooth, large boulder formations and rocky outcrops for basking on, with adequate crevices and sheltered areas for retreating into.

They will immediately flee into the rocks and crevasses to hide from predators such as humans, birds of prey, feral dogs and cats.

Their long claws can also cause significant scratches (even drawing blood), though this is not necessarily a defensive act, but can simply result from handling a more friendly iguana.

[9][13] A study in 2000 by Dr Allison Alberts of the San Diego Zoo revealed that seeds passing through the digestive tracts of Cyclura species germinate more rapidly than those that do not.

[15] The rhinoceros iguana is also an important means of distributing these seeds to new areas (particularly when females migrate to nesting sites) and, as the largest native herbivores of their island's ecosystem, they are essential for maintaining the balance between climate and vegetation.

[15] Rhinoceros iguanas do appear to be opportunistic carnivores, as individual animals have been observed eating small lizards, snakes, land crabs, insects, and carrion (especially dead birds and fish).

Male rhinoceros iguanas, unlike other members of the genus Cyclura, reach sexual maturity at four to five years of age.

[20] A successful breeding program existed at the Parque Zoológico Nacional of the Dominican Republic (ZooDom) from 1974 to 1994, with an average of 100 babies hatching annually.

[1] These efforts included reintroductions of captive-bred "head-started" young to several protected areas in the southwest Dominican Republic, in order to reduce the odds of predation by snakes and introduced carnivorans, such as mongooses or feral cats and dogs.

[3] Illegal logging, competition from domestic grazers (cows, pigs, goats), predation on young by invasive species, limestone mining, harvesting for the pet trade, hunting for bushmeat, pollution, and wildfires are all manmade threats to the rhinoceros iguana's survival.