Tourism is destroying valuable wetlands and threatening water supplies in the
Mediterranean, a WWF report claims.
The activities of tourism could threaten internationally recognised wetlands
It warns an expected boom over the next 20 years, with tourist numbers set to reach 655 million people annually by 2025, will strain supplies further.
Golf courses and swimming pools will continue to be built, adding to pressure on water demand.
France, Greece, Italy and Spain have already lost half of their original wetland areas, the report says.
It adds that the annual consumption of a golf course is equivalent to that of a city of 12,000 inhabitants and a tourist staying in a hotel uses on average one third more water than a local inhabitant.
The report cites examples of internationally important wetlands which are being destroyed by tourist activities.
Tourism expansion near Spain's Donana National Park is competing with the park's wetlands for already scarce resources.
The WWF fears that resorts planned on the Moulouya estuary in Morocco could further threaten the endangered monk seal and the slender-billed curlew, one of the rarest birds in Europe.
Holger Schmid, of WWF's Mediterranean Freshwater Programme, said: "The tourism industry's growing demand for water-guzzling facilities and services, such as water parks, golf courses and landscaping, is destroying the very resource it depends on.
The conservation group says the problem is responsible for pollution, shrinkage of coastal wetlands and the tapping of non-renewable groundwater in some regions.
The problem is compounded by the fact the peak summer season for tourists coincides with the period when irrigation needs are greatest in agriculture, WWF claims.
The total number of tourists heading for Mediterranean coastlines is expected to rise to between 235 to 355 million per year by 2025 - roughly double 1990 levels.
WWF said local authorities in tourist hotspots tended to tackle the booming demand for water by increasing supply, which in the long-term is not sustainable.
It said governments were pushed into ever more drastic and costly measures to get large quantities of water to arid regions, citing a 3.8bn euro ($4.69bn) Spanish plan to divert water from the Ebro river in the fertile north to the south east.
The new Spanish government has just scrapped the plan, which faced fierce opposition from environmentalists and the regions that were going to lose water.
Instead, WWF said, authorities should focus on reducing demand. Installing simple, cheap devices such as water-saving taps and toilets can reduce consumption by up to 50%.