Natrix maura is a natricine water snake of the genus Natrix. Its common name is viperine water snake or viperine snake. Despite its common names, it is not a member of the Subfamily Viperinae. This nonvenomous, semiaquatic, fish-eating snake was given its common names due to behavioural and aesthetic similarities with sympatric adder species. It looks like an adder and behaves like one. It is known to strike like an adder but not bite. On the other hand, when in water, the viperine snake then looks like a grass snake and hunts its prey in the same way. The viperine snake should really be called the viper grass snake. In the small areas of England where it breeds in the wild it is usually mistaken for an adder and vice versa. This snake is diurnal.