This is a beautiful part of Vietnam, even more beautiful when you can see past all the tourist boats. There were seven passengers with Chi, our guide, on the bus from Hanoi and on the cruise boat: Frances and me, another (somewhat younger) Australian couple, a (younger again) Singaporean man, and two (younger still, I think) Australian girls. I lost count of the crew, about four at a rough estimate, and at least one of them was an excellent cook.
Advice to would-be tourists on these cruises: There are very many boats all very similar (meant to look like junks), all the same colour and with similar names. You should remember your boat's number; otherwise, when you get back after the stop to walk through a cave or one of the other island stops, you might get on the wrong one or think yours has gone without you; it won't necessarily be where you left it.