In most cases, holidays are a chance to do whatever you want – whether that's a long weekend museum hopping or a 10-day vacation sat on the beach reading Harry Potter. 

There are, however, certain holiday activities that can veer into the ethically dodgy realm. 

Here are six things you really shouldn't be doing. 

Riding elephants

Maybe it's a friend on their gap yah adventures or your sister "finding herself" in Laos. Maybe you've been tempted yourself. Whatever the situation, it can often seem like a snap on the back of an elephant is an "obligatory" tick-box exercise on any Southeast Asian travel itinerary, but it is also fueling an exploitative and barbaric practice that sees babies taken from their mothers and forced to live a life starved of interaction with other elephants. According to a 2017 report from World Animal Protection (WAP), as many as 75 percent of these elephants are living in "severely cruel" conditions, often bound in chains no more than 3 meters (10 feet) long and subjected to physical abuse by their keepers.  

If seeing an elephant is an absolute must on your bucket list, there are sanctuaries out there that allow you to watch them in a more natural setting – and from a distance.  

Or dolphins for that matter

Dolphins appear to have a permanent grin plastered on their faces so it might look like they're having a good time but the ones found in marine parks definitely aren't.

Many have been captured from the wild in order to fulfill the demand for dolphin experiences. Often they die in the process, while those that make it are condemned to live a short and stressful life trapped in a tank, isolated from their fellow dolphins, and away from their natural environment. That's not even starting on the cruel practices you see in some marine parks – see, for example, ones in Thailand that remove teeth. Even those in the wild can be threatened by habituation if they are exposed to too much contact with humans, as the recent example of France's horny dolphin goes to show. 

Besides, if The Simpsons has taught us anything, it is that you really don't want to mess with these cetaceans. 

Taking selfies with tigers

While we're on the subject of animals, taking a selfie with a tiger is another bucket list goal you should probably skip. Not only does it make you look like a dick, you will have to accept the fact that you are supporting an industry that keeps wild animals chained up, beaten, and heavily sedated just so you can take a photo with a big cat and not have your head bitten off. Remember the famous "tiger temple"? It finally closed down after two decades but not before police discovered 40 tiger cub carcasses in its freezers. 

It's not just tigers, however. Tourists may be under the illusion that these animals are being looked after but the slow loris, monkey, and any other exotic animal you might pose with on holiday was likely poached from its natural habitat just so that its owner can make money from other people's selfies – and then discard it when it is no longer "photogenic".

Harvesting coral 

Corals are having a hard enough time what with water acidity, major bleaching events, and crown of thorns starfish before you add thieving tourists into the mix. Mass tourism (along with climate change and overfishing) is one of the major reasons behind the decline in coral reefs worldwide. Half the coral in the Great Barrier Reef, for example, has died since 2016 and experts are now worried it will never recover.

Reef Teach, an Australian-based education center, warns that stepping on and even touching the reef can damage the coral or make it more susceptible to infection by removing its protective mucus. They also recommend limiting souvenirs to memories and photos (or, perhaps, the odd piece of plastic) to make sure the reef remains healthy, happy, and there for visitors in the future. If you absolutely must get a small piece of coral for your private collection, the Australian government provides guidelines on exactly where and how to do so.

Watching a bullfight

The Running of the Bulls (or Festival of Saint Fermin) in Pamplona, Spain, is one of the country’s most famous – and controversial – traditions, seeing more than a million pour into the medieval city each and every year, reports USA Today. The practice sees bulls chased with sticks and rolled-up newspapers down an 875-meter (2,870-foot) racecourse before culminating in matador fights (and almost certain death, at least as far as the bulls are concerned).

Bullfighting has existed in some format or another since Roman times and like all ethically problematic cultural traditions, the debate on whether to ban, restrict, or continue said tradition is a particularly sticky one. However, as a tourist, you can choose whether or not to contribute time and money to the blood sport. For an equally lively and much less controversial Spanish festival, there is always La Tomatina.

Visiting places already overrun with other tourists

The rise of budget airlines, large-scale resorts, and short-term rentals (looking at you, Airbnb) means every Tom, Dick, and Sally can hop aboard a plane and visit extraordinary locations that our grandparents could only dream of. This can be a good thing – think: the economic and personal benefit of travel – but you know what they say about too much of a good thing. In this case, it can lead to overtourism and destruction of the natural habitat. (Not to mention angry residents.)

Perhaps, the best-known example of this is the beach from The Beach, which is actually Hat Maya beach on Phi Phi Leh Island, near Phuket, Thailand. Back in the 90s, when Danny Boyle began filming, it was a little-known destination. Now, as many as 5,000 paradise-seeking tourists step onto its shore every single day, The Telegraph reports, degrading the reef and threatening marine life. It is for this very reason, Thai officials made the decision to indefinitely close the island this year.

It's not just Hat Maya that's at risk of overtourism. It's Boracay in the Philippines, Machu Picchu in Peru, Venice in Italy, and Bali, which is swamped in plastic garbage. More recently, the Rainbow Mountain of Peru has attracted attention. Only discovered five years ago (and probably as a result of climate change), it is now drawing crowds of up to 1,000 a day and a 2.5-mile (4-kilometer) trail has already been seriously eroded.

Whether it's avoiding peak travel season or tourist hot spots, there are ways to travel sustainably without contributing to the problem.