While the lake draws comparisons with Ha Long Bay, and while it's not quite on the same level, it's still a truly beautiful area worthy of exploration.
The lake is huge -- it sprawls across an area of more than 23,000 hectares, stretching 80 kilometres long and up to 10 kilometres wide. Its deepest point plunges down 42 metres. The dam created 1,331 islands, mostly covered in forest and surrounded by still, clear water. It really is picture perfect -- when the sky is blue at least.
Boat trips and treks are possible around the lake and as you float around between the islands or look down on the lake from one of the vantage points, it's strange to think that this whole area was once a valley where people lived and worked. The many islands would once have been hills and mountains.
Although you can get to Thac Ba lake independently, it's not a developed tourist location with really just one place to stay -- La Vie Vu Linh, an eco-lodge on the banks of the lake. We'd suggest either booking onto a tour from Hanoi or Sapa or booking an overnight stay at the eco-lodge.
The Travelfish newsletter is sent out every Monday and is jammed full of free advice for travel in Southeast Asia. You can see past issues here.