Popularity threatens to turn a once romantic destination into a sewer.

Before managing the Barracuda diving club in Goa's Sun Village resort, Venkatesh Charloo worked on a trading desk in a Hong Kong bank. After watching a Cousteau film he decided to quit the world of finance and get into deep sea diving. Now, 15 years later, he is very angry. "The islands off Goa are covered in garbage, and there are fewer and fewer fish." Part of his job is to clean up diving sites at the beginning of the tourist season.

Goa survived four centuries of Portuguese colonisation and an influx of hippies in the 1960s, but today it is threatened by mass tourism. More than 2.5 million tourists visit this small state in south-west India every year, twice as many as 10 years ago, with a local population of just 1.5 million. National Geographic has ranked Goa's beaches among the worst in the world.

Few would complain about the cows lying on the sand under the parasols. They are, after all, sacred, but beer bottles and plastic bags litter most beaches and only the distant sunsets remain untouched. They are what made Goa's reputation as a romantic destination, with local government advertising urging travellers to make their wives their girlfriends again.

However, the proliferation of faecal coliform bacteria may well disturb the promised idyll. According to a study by the Goa based National Institute of Oceanography, levels of potentially dangerous bacteria, such as salmonella, rose sharply between 2002 and 2007. The report, published last July in the journal Ecological Indicators, concluded that increasingly strong concentrations of faecal coliform and other pathogenic bacteria in the coastal waters were a threat to the environment as well as to human health. In some places, swimming could lead to disease .

At the mouth of the Mandovi river, currents sweep sewage down from the hotels, along with residue from pesticides used by the farmers up country, and the sediment from nearby mines. Underwater visibility has been considerably reduced. "You can't see further than your own nose now," said Ajey Patil, a deep-sea diving instructor. {Read on}