Widely adapted and common, the terciopelo is no stranger to lowland moist and wet forests and premontane moist, wet, and rainforest. It is less common through dry forest zones, although it may persist along rivers through such forest. In human-controlled areas where rat populations have done well, this viper is not shy. Banana plantations are a particular haunt of the terciopelo because of their rats.
In Costa Rica this species is common along the lowlands of both coasts up to 1,300 m in elevation. Beyond this country, it can be found on the Pacific coast from some parts of Mexico down to Ecuador; on the Atlantic coast, down to Colombia.
Corcovado National Park, Golfito National Wildlife Refuge, La Selva, Chirripó National Park, Carara National Park, Tortuguero National Park.
This snake can grow to a large size as an adult, but has a distinct coloration pattern both as a juvenile and adult. Pale yellow or cream-colored bands crisscross the back and sides of the body, making spaces for a dark diamond pattern. The luster of these dark triangles is velvety, and the triangles connect slightly on the back which some describe as a butterfly or hourglass pattern. The head is large, triangularly shaped, and conspicuously wider than the neck. This pit viper has the deep, visible, heat-detecting pit between each eye and nostril. The eyes are large and have a vertical pupil. The scales along the head and back are keeled.