An American couple got a rude awakening to cultural and legal differences during a recent trip to Venice.

Julia Latoff and her boyfriend, endurance athlete Mike Naccarella, were vacationing in Italy last month when they went for a run through the historic canal city.

Latoff told The New York Post that the couple regularly exercises when they’re traveling, and noted that they planned the run for early in the day when the city’s narrow streets were likely to be less crowded.

“Running while we’re traveling is something we do to get to know the city and to sightsee,” she told the paper.

Things got weird fast. The couple noticed shortly into their run that they were attracting displeased glares from the locals.

“Within the first 5 to 10 minutes, Mike noticed people looking at him and giving us glances. We knew something was off, but we weren’t sure exactly what it was,” Latoff said.

The nasty looks they were receiving were the result of a decision Naccarella made at the start of his run; he took his shirt off.

“This isn’t a beach!” a local reportedly yelled at them.

Latoff said in an Instagram post that Naccarella had run shirtless in Florence earlier in the week and saw other shirtless runners were doing the same, so she did not think it would be an issue in Venice.

Naccarella said he did an internet search to see why he might be getting such a negative reaction from the Venetians, and found that it is actually illegal to go out in public in Venice without a shirt on or wearing swimwear.

Visitors who break the rule can be fined up to €250 ($290).

That law was adopted in 2018 to preserve a sense of respect around the city’s various cultural and religious landmarks. Venice is home to St Mark’s Basilica — where the remains of St. Mark are said to be held — and the Santa Maria della Salute, which pays tribute to the Virgin Mary.

Once the runners realized what was going on, they stopped their run. Naccarella told the paper that he always tries to adhere to local laws and customs when he travels.

However, the couple was already two miles away from where they were staying, and Naccarella didn’t want to run back shirtless. His sister’s fiancé, who was running with the couple, volunteered to buy him a shirt from a tourist shop.

He ended up wearing a “Creation of Adam” Aperol Spritz t-shirt on the run back.

The couple shared a video about their experience on social media, which drew the usual slew of commenters complaining about American tourists abroad, though some at least were complimentary to Naccarella’s physique, which he called “flattering” despite his embarrassment in the moment.

Latoff said that she hopes other travelers can learn from their mistake and avoid awkward situations on their own trips.

“Everyone has the right to travel and explore, and hopefully, everyone can learn from our lesson and make sure that they’re mindful of the culture,” she said.