Vietnam's Ha Long Bay was recently named one of the new "Seven Wonders of Nature", and the area has made it on the UNESCO World Heritage list twice.

Around six million people visit the area each year, and the 1,500-square-kilometre site is feeling the environmental consequences of mass tourism.

Balancing the site's natural value against the lure of the tourist dollar is a challenge faced by Hanoi. 

The strategy is to keep the tourist numbers growing, but spread them to the lesser known areas of Vietnam.

If not, Ha Long Bay may lose the very beauty that tourists now flock to see.

Al Jazeera's Aela Callan reports from Vietnam.