Green Iguanas (Iguana iguana) are the largest species of lizard in Costa Rica. These spine-crested lizards can reach up to 6.5 feet (2 m) in length and weigh up to 17.6 pounds (8 kg). This particular adult Green Iguana was not one of the largest ones that I observed, but it was the greenest adult that I could find.

Adult Green Iguanas can be green, gray, brown, and even tinged black. The females are more likely to be green, while the males may be bright orange or gold during courtship.

Adult Green Iguanas are arboreal and spend their time either lounging on tree branches and soaking up the sunlight or munching on green leaves and ripe fruit. Green Iguanas are often seen basking on branches overhanging the water, and they will quickly dive in and swim away to escape predators.

Green Iguanas may get their common name from their brilliant emerald green juveniles.

Unlike the arboreal adults, juvenile Green Iguanas are often found on the ground, where their brilliant green coloration blends in quite well with the grass, but contrasts sharply with the brown soil.