Activities such as feeding pigeons and wearing camouflage clothing could land British holidaymakers in trouble with the law, the Foreign Office has warned.
The FCO has listed some of the more unusual international crimes in its latest travel advice.
"It's a good idea for Brits to research the country they are visiting before they travel," advises the FCO's Charles Hay.
Here are 10 ways Britons can fall foul of police abroad (crimes punishable with a fine unless otherwise stated):
Strictly prohibited on the Mass Rapid Transit (MRT) system in Singapore.
Against the law in Venice.
Wearing swimming trunks
As well as wearing a bikini or going bare-chested, in Barcelona this is illegal if you're not in the beach front area.
Using nasal spray
Some common products are illegal in Japan.
In Saudi Arabia, taking a snap of a palace, government building or "military installation" can land you in jail.
In Barbados it is an offence for anyone, including children, to dress in camouflage clothing.
Prohibited in Fiji.
Carrying mineral water
It is illegal to take mineral water into Nigeria.
Snacking while sightseeing
In Florence, it is an offence to eat and drink in the immediate vicinity of churches and public buildings.
In the Maldives, public observance of religions other than Islam is prohibited for visitors. Punishable by arrest and detention.