We spent a significant amount of time and effort doing reasearch into selecting the right tour company - we had been warned that there are many places with same name trying to sponge off the original location with a good reputation and many horror stories of bad boats, rats, etc... However, our reseach paid off and we found ourselves on a fantastic tour with a great group of people (Ocean Tours for anyone interested)
A UNESCO World Heritage Site, Halong Bay is a stunning setting with over 1,000 karst islands. There are hoards of tourist boats and so unfortunately lots of litter and diesel on the water, definitely not a place to take a nice swim (although the booze-cruise we saw later didn't seem to care as at least 10 people dived off their boat after more than a couple of beers from the looks of things).
The Vietnamese hopes for Halong Bay to become one of the new 7 natural wonders of the world will mostly likely be unsucessful because despite the fact that it certainly has the dramatic landscape, it would be a poor embassador for natural beauty given the bad liter and pollution problem.
The first night of our trip we stayed on a lovely private island in a very nice bungalow. The food was fantastic - 5 or 7 courses, we lost count! On our way to the island, our boat broke down and as we bumped off nearby island rock outscrops the captain feared mutiny and offered a free bottle of 'Dalat' vietnamese wine - tasted great and shared between the 14 of us.
The second night was spent aboard a boat - we all had our own cabins with bathroom (even a hot shower!) and as we luckily weren't near the engine, as some had been, we had a blissfully peaceful nights sleep.
The weather was rather hazy but it added to moody effect of the islands. Luckily no rain though.