Every year nearly 700 million trips are made abroad.

Developing countries are increasingly turning to the tourist dollar to boost national earnings and create jobs.

But the search for “unspoilt” places brings visitors to some of the world’s most fragile and beautiful environments.

Providing facilities such as flush toilets, air conditioning, swimming pools and golf courses can put a huge strain on regions where water and power are in short supply.

Air transport is also one of the world’s fastest growing sources of the greenhouse gases which contribute to climate change.

By some measures tourism is the world’s largest industry. But it is also one of the least regulated industries.