Vietnam's Ha Long Bay losing its hue

Vietnam's Ha Long Bay is losing its famous turquoise hue as pollution and over-development threaten its wildlife and picture-perfect image. 

The UNESCO site is one of Vietnam's most popular tourist destinations, with more than seven million people visiting its blue-green waters and rainforest-topped limestone islands last year. 

But the bay's popularity, and the subsequent rapid growth of Ha Long City have severely damaged its ecosystem. The surrounding town is already heavily developed, with docks and luxury apartments blocking the shoreline. 

  Conservationists estimate there were originally around 234 types of coral in the bay -- now the number is around half. There is also a huge problem with both human and plastic waste.