To millions of tourists they are exotic paradises, unspoilt, idyllic and full of local charm. But many of the world's resorts are struggling to cope with relentless waves of tourists, whose demands for ever more swimming pools and golf courses are sucking them dry.
Springs and underwater aquifers from Ibiza to Barbados are being drained faster than they can be replenished, or irreversibly polluted by overdrilling. By 2025, the number of people living in areas where renewable water is scarce will increase from 130m to more than 1bn, much of it fuelled by booming tourist development.
"The issue is massive and global," says Tricia Barnett, director of Tourism Concern, a charity which campaigns for more responsible approaches to travel."Tourists in Africa will be having a shower and then will see a local woman with a pot of water on her head, and they are not making the connection. Sometimes you'll see a village with a single tap, when each hotel has taps and showers in every room."
Southern Spain and the Balearic islands, favourites with British holidaymakers, are getting drier by the year, as ancient springs and underwater aquifers dry up. Of the seven underground springs on Ibiza, five have been so over-drilled that sea water has seeped in, making the water unsuitable for drinking or ir rigation.
Benidorm's water table is now so low - and the demand from its 30,000 swimming pools so insatiable - that it has to pipe much of its water along a 300 mile pipeline from Madrid.
The problem is that tourists demand so much water. WWF (formerly the World Wide Fund for Nature) has calculated that a tourist in Spain uses 880 litres of water a day, compared with 250 litres by a local. An 18-hole golf course in a dry country can consume as much water as a town of 10,000 people.
The UN food and agriculture organisation has estimated that 100 tourists use the same amount of water in 55 days that could grow rice to feed 100 local villagers for 15 years. Village wells in Goa are running dry, and rivers are being polluted by effluent released from hotels. In the Caribbean, hundreds of thousands of people go without piped water during the high tourist season, as springs are piped to hotels.
Tourism is the fastest growing industry on the planet. In 1950, 25m people travelled abroad; in 1999 it was 670m. The World Tourism Organisation estimates that by 2020 1.6bn people will travel each year.
The growth area is long haul travel. It is growing by 9.5% a year in developing countries, as tourists tire of the Costas and head for more exotic locations like Thailand and Brazil, once the preserve of backpackers.
"In many resorts, there are insufficient controls," says Justin Woolford, tourism officer for WWF. "The implication is that it's the fault of the local government, but there's quite a large responsibility with big tour operators when they go to a new destination. They will tell you they have no influence over infrastructure, but that's not true."
The country may not see many benefits. Poor governments often offer tax-free incentives to developers, who then build all-inclusive resorts where very little of the income reaches the local economy. In Thailand, 60% of the £4bn annual tourism revenue leave the country.
Geoffrey Lipman, executive chairman of Green Globe 21, which offers accreditation to travel companies incorporating ethical principles, said: "The message to governments is that tourism has a much bigger impact on your economy than you give it credit for in your policymaking." Local communities are beginning to say enough is enough. The Balearic islands voted to impose a 60p tax per day on each traveller, to address problems caused by hasty development in the 60s and 70s.
Attitudes are changing, says Ms Barnett, but slowly. "We like to believe there's consumer power out there. Ask your tour operator where the water in your hotel comes from. Who owns the hotel?The travel agent will look bewildered, but if consumers start asking these questions, operators will start asking them too."
