The document discusses the Mediterranean Sea and pollution issues affecting it. It notes that while the Mediterranean was once described as the world's largest swimming pool, it is now considered the world's dirtiest sewer due to large amounts of rubbish, oil, chemicals and waste from surrounding countries. Some countries want to start cleaning up the Mediterranean, but others have begun expanding oil and gas development which could worsen pollution. Three major rivers that flow into the Mediterranean also carry large pollutant loads, making the water very dangerous.