Large, stout viper with narrow, flat, triangular head. Colour pattern complex with 15-18 oblong blue or blue-green markings down the centre of the back, these are enclosed in irregular black blotches, along the flanks are a series of dark crimson triangles narrowly bordered with blue or green. Top of the head is blue or green with a vivid black arrow mark. Belly dirty white to dull green with extensive blotches. Length up to 120 cm.