Terciopelo is a species of pit viper occurring at low to moderate elevations in northeast Mexico and Central America, and into South America where it is known from elevations up to 2600 meters in the Colombian and Ecuadorian Andes, as well as Venezuela and Trinidad on the Caribbean coast. With a mass up to 6 kilograms and the maximal length of 2.5 metres, terciopelo is among the largest pit vipers. It is light to dark brown in color, often with yellow zig-zag-shaped line on each side of the body. Dubbed "the ultimate pit-viper" for its large size, fangs and venom yield, it has a fearsome reputation, responsible for the most snakebites within its range because of its defensive temperament and proximity to human residence. However, in common with other venomous snakes it avoids confrontation with humans whenever possible.