At the crossroads of three continents, the Mediterranean is the largest semi-enclosed sea in the world.
By 2020, half of the Mediterranean coastline may be built upon
Over the ages, it has supported a vast array of wildlife.
About 150 million people also live within 20km of the Mediterranean, and each summer that population almost doubles as swarms of sun-seeking tourists pack the region's hotel rooms.
But what they come to enjoy is slowly being destroyed.
After more than a quarter of a century of international treaties and plans to save the sea, the battle is on to stop the last pieces of untouched coastline being covered in concrete.
The issue is featured in Concrete Coasts, a film in the Earth Report series made by TVE and shown on BBC News 24, BBC One and BBC World.
Within living memory, the sea has teemed with whales, dolphins, seals, turtles, and fish. Large sea grass meadows support much of this chain of life.
But the boom in tourism over the past 50 years has placed this amazing biodiversity under threat, says the TVE programme.
"One of the major threats is from mass tourism development along the coastline of the Mediterranean," Paolo Guglielmi, of conservation organisation WWF Mediterranean, told TVE.
"This is extensively damaging the environment and the ecosystem by occupying coastal land which is very fragile and by producing an enormous amount of liquid and solid waste on top of using a lot of energy."
Today, the Mediterranean is the world's most popular holiday destination. Escaping to the sun every year, 220 million holidaymakers - mostly from North European cities - flock to its coasts.
Every year, the numbers are growing. By 2020, they are projected to reach 350 million people - the population of the United States. Germany is the largest market followed by the United Kingdom, France and Italy.
On the Costa del Sol today, there is hardly a break in the coastline development from Malaga to Gibraltar. This urban conurbation is now so big it is being referred to as Spain's second biggest city.
Buildings also dominate the coastlines of France and Italy and by 2020, it is expected that half of the 46,000km of Mediterranean coastline will be built upon - with much of the development linked to the tourist sector.
Between Spain and Sicily, 75% of sand dune habitats and their biodiversity have been destroyed by tourism-related urbanisation.
The loss of natural habitats has led to more than 500 plant species in the Mediterranean being threatened with extinction, according to WWF.
The destruction continues unabated, despite decades of initiatives intended to save the Med, including a UN Action Plan.
As well as continuing construction, the vast influx of holidaymakers every year puts a huge strain on resources and creates a vast amount of waste on shore - far too much of which ends up in the sea.
"The impact of tourism on the Spanish resources has been really large and what we've found is that building and water are the two single largest impacts," Xavier Font, from Leeds Metropolitan University, UK, told TVE.
Millions of tourists flock to the Mediterranean each year
Freshwater supplies are reaching crisis point in some Mediterranean countries, particularly the islands of Spain and Greece where they have little rainfall, small catchment areas and limited storage.
Throughout the holiday season, consumption of freshwater supplies rockets. The average Spanish city-dweller uses about 250 litres of water per day, while the average tourist uses nearly twice as much.
This is not just for personal use. Hundreds of millions of litres fill swimming pools, which are very often located within just a few metres of the sea.
Other water guzzlers are golf courses which consume more than 2.3 million litres of water every day. Every year, 5,000 hectares - half the size of Paris - is cleared to make way for them.
On top of that there is the damage caused by increases in waste and pollution. The Mediterranean sea receives about 10 billion tonnes of industrial and urban waste every year with little or no purification.
In high season, the production of waste from tourist areas often exceeds the capacity to carry it.
To investigate the effect tourism-related coastal development was having on the environment, WWF combined data on major species like turtles, seabed habitats, and human settlements, and produced a complete conservation map of the Mediterranean.
The map shows that most of the Mediterranean coastline has been affected to some extent by urbanisation, mostly tourism-related.
But from Gibraltar, along the French coast to the Italian Border, the Italian Adriatic coastline, and the Syrian coastline to Egypt, all natural ecosystems have been annihilated. Most in the last 30 years.
Despite this, loggerhead and green turtles, and 19 species of whale and dolphin hang on there. Most endangered of all is the monk seal. Ten enclaves of pristine wildlife and unique culture, once the hallmark of the Mediterranean, now face being wiped out, TVE reports.
Despite three decades of environmental awareness, less than 5% of the Mediterranean coastline is protected - way below the minimum set by WWF.
"We must switch now to more responsible tourist practices which are in harmony with nature. If we don't do this, the Mediterranean will become nothing more than a huge dead swimming pool," says Mr Guglielmi.
But there is hope, TVE says. WWF is working with tour operators, local communities, and governments, to try to preserve the last pristine habitats and manage the impact of tourism in a sustainable way.
One step forward was the creation of a whale and dolphin sanctuary in the north-western Mediterranean between Sardinia, the Cote D'Azur and the Italian Ligurian coast.
Covering 84,000 sq km and the home to 18 different species of whales and dolphins, it is the first marine protected area in the northern hemisphere to include international waters.
In the summer months, these are rich feeding grounds for up to 2,000 whales and more than 40,000 striped dolphins. Yet these waters are becoming increasingly polluted with untreated sewage and other waste from urban and industrial areas.
Monk seals are threatened by continued development
Other threats include driftnet fishing which unintentionally kills dolphins, and increased marine traffic from ferries, speed boats and whale-watching tourists.
To regulate these activities, including a ban on drift netting, the Italian, French and Monaco governments recently agreed a management plan for the sanctuary and the challenge now is to enforce it.
The sanctuary is so large - twice the size of Switzerland - that policing it requires the combined, co-ordinated and sustained resources of all three countries involved to make an impact.
Further marine protection areas are being opened in biodiversity hotspots in the Eastern Mediterranean.
On Lastovo island, Croatia, conservationists and local government have set up the first in a string of marine protection areas that will form a "blue corridor" along the Dalmation coast, an area expected to be one of the hottest new holiday destinations over the next 15 years.
Conservationists would also like to see Turkey adopting the idea of marine protection areas to care for underwater habitats such as the important Posidonia sea grass meadows, as well as its sealife and sunken ruins.
"The lesson really that tourism destinations should learn from Spain is that they shouldn't sell cheap," says Dr Font.
"Turkey and Croatia should understand that if they have something worthwhile offering they will get tourists coming to that place because of what they have. So reducing the prices, because in the short term they can do that, is really problematic."
But what of the concrete coastline of Spain? Has its natural environment been lost forever? There are now signs that tour operators and local leaders are changing course.
"In those cases where the destination has overdeveloped, where it has gone over the critical limit of development, one of the only solutions is that you demolish hotels, you create green areas, you rehabilitate the beach areas, you try to bring back some of the biodiversity," said Dr Tom Selanniemi of the Tour Operators Initiative for Sustainable Tourism Development.
"In Majorca, for instance, they have already started to blow up some of the hotels which I think is a good idea to make these destinations pleasant once more."