Did you know that it's illegal to wee in the sea in Portugal, or wear high heels in Greece?

Before you head off on your summer holidays, it might be worth checking up on some of the more unusual local laws, just so that you don't get into trouble for doing things that are completely legal at home.

With this in mind, visa application website GlobalVisas.com has put together a list of ten of the strangest laws in different countries around the world as part of their Know Before You Go campaign.

Some of the obscure rules might come as a bit of a surprise. For example, did you know that it's illegal to feed the pigeons in St Marks's Square, Venice? You'll face a fine if you get caught doing it because the authorities are trying to reduce pigeon numbers.

Motorists need to take extra care in Germany, where it's illegal to run out of fuel on the autobahn. It's a criminal offence to drive in flip-flops in Spain, and Danish law stipulates that you need to keep your headlights on at all times, even during the day.

It pays to watch your manners, too. You'll end up with a fine if you're caught swearing in Virginia Beach in the US, and the same goes if you spit in public in Barcelona, Spain. In Singapore, it's an offence to chew gum - unless it's medicinal.

Think twice about what you wear in your feet if you're visiting historic sites, such as the Acropolis, in Greece. High heels have been banned to reduce the risk of damaging ancient monuments.

In the UAE, you could face a prison term if you eat in public during Ramadan, and be careful not to step on currency in Thailand, where the Thai baht carries the image of the revered King of Thailand.

It's also wise to bear in mind that it's illegal to wee in the sea in Portugal, and that it's a legal requirement for people in Milan to smile at all times, unless attending a funeral or visiting hospital.

Obviously, some of these would be virtually impossible to enforce, but others really could cause problems for travellers.

Gary Smith of GlobalVisas says: "Generally having a clear sense of right and wrong will help you get by in life and enable you to stay out of trouble. However, it seems that in some cases, the law isn't necessarily clear cut.

"Whilst we would advise people to be aware of differences in culture that could cause some misunderstanding, some of these laws are likely to take even seasoned travellers by surprise. But ignorance is no excuse in the eyes of the law. If you're travelling, you need to be aware of local sensibilities, even if they do seem a bit obscure!"

Click on the image below to see some of the strangest items seized by customs...

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