Every year 100 million holidaymakers are drawn to the Mediterranean. With one third of the world's tourist trade, it is the most popular of all the holiday destinations; it is also the most polluted. It has only 1 per cent of the world's sea surface, but carries more than half the oil and tar floating on the waters. Thousands of factories pour their poison into the Mediterranean, and almost every city, town and village on the coast sends its sewage, untreated, into the sea. The result is that the Mediterranean, which nurtured so many civilizations, is gravely ill the first of the seas to fall victim to the abilities and attitudes that evolved around it. And the pollution does not merely keep back life of the sea it threatens the people who inhabit and visit its shores. The mournful form of disease is caused by sewage. Eighty five per cent of the waste from the Mediterranean's 120 coastal cities is pushed out in to the waters where their people and visitors bathe and fish. What is more, most cities just drop it in straight off the beach; rare indeed are the places like Cannes and Tel Aviv which pipe it even half a mile offshore. Not surprisingly, vast areas of the shallows are awash with bacteria and it doesn't take long for these to reach people. Professor William Brumfitt of the Royal Free Hospital once calculated that anyone who goes for a swim in the Mediterranean has a one in seven chance of getting some sort of disease. Other scientists say this is an overestimate; but almost all of them agree that bathers are at risk. Industry adds its own poisons. Factories cluster round the coastline, and even the most modern rarely has proper waste treatment plant. They do as much damage to the sea as sewage. But the good news is that the countries of the Mediterranean have been coming together to work out how to save their common sea.