Nerodia rhombifer

The diamondback water snake is predominantly brown, dark brown, or dark olive green in colour, with a black net-like pattern along the back, with each spot being vaguely diamond-shaped. Dark vertical bars and lighter colouring are often present down the sides of the snake. In typical counter-coloured fashion, the underside is generally a yellow or lighter brown colour, often with black blotching.

The scales are heavily keeled, giving the snake a rough texture.

Adult males have multiple papillae (tubercles) on the under surface of the chin, which are not found on any other species of snake in the USA.

N. rhombifer grows to an average total length (including tail) of 30-48 inches (76–122 cm). The record total length is 69 inches (175.3 cm)