The Viperine Water Snake (Natrix Maura) is the smallest of three members of the genus Natrix occurring in Europe. 
The Viperine Water Snake is a variable species in terms of colour and pattern. 
The ground colour usually ranges from light grey, grey-green, sandy brown to dark brown. 
There are even red coloured animals. 
There are snakes that show little or no contrast, animals with a clear contrast in the form of spots and/or a zigzag pattern. 
You can see them often in the water where they hunt for fish.

The Viperine Water Snake may have a contrasting zigzag design and superficially resemble members of the genus Vipera, hence the name Viperine Water Snake. 
Furthermore, this similarity with vipers is reinforced by their behaviour. 
When threatened they can hiss loudly with a flattened head and body and strike like a viper, but it will not bite. 

The Viperine Water Snake is found in southwestern Europe and northwestern Africa.

Bridge over Arroyo de la Vid, near Monfragüe National Park, Extremadura, Spain, 12 June 2024