Venice is sinking. Each year more than 25 million tourists descend on the city with a residential population of just 53,000. Massive cruise ships, 'eat & run' tourists and rising sea levels all compound the strain. Venice may be a world treasure, but Venetians are disappearing – fast.  In just a decade the city has lost 12 per cent of its resident population, which now sits at just 53,000.  Some locals say they’ll all be gone in a few decades.