The Italian authorities have repeatedly warned visitors: Fountains aren’t for wading.

There’s a law on the books, promising fines for offenders. But amid one of the hottest summers in Europe, the rules didn’t stop two men from pulling a tourist stunt in a famous fountain in Rome this week, and causing a public outcry.

The two men decided to hop into the fountain to pose for photos in their underwear beneath the Altar of the Motherland, which also holds the tomb of the unknown soldier. There, at a monument celebrating the unification and liberation of Italy, and commemorating its more than 500,000 dead in World War I, one decided to drop his underwear.

The cellphone footage, shared widely on social media, enraged Italian officials, who called it an insult.

Rome’s police — who posted pictures of the episode on Monday, describing it as “an outrage to the unknown soldier” — are hunting for the culprits, described as “English speakers.”