With temperatures topping 30 degrees Celsius (86 degrees Fahrenheit), keeping cool is tough at the best of times and if you happen to be covered from head to foot in orange fur, sometimes there's nothing for it but to reach for the hose.
Vienna Zoo made sure its three orangutans had plenty of opportunities to make a splash on Tuesday, and they took full advantage.
Keeper Fredi Maier says the trio like to keep cool in different ways.
Male Vladimir likes to shower himself down with a hose, or bucket, while Sol fills plastic cups of water for a refreshing drink.
Perhaps most sensible of all is 55-year-old female, Mota, who prefers to shelter from the hot sun under a wet blanket.
The hot weather is likely to remain for several days as a heatwave sweeps Europe, with temperatures set to rise to more than 40 degrees Celsius (104 degrees Fahrenheit) in Vienna.