Same limestone, three different trips
Choosing the water matters more than choosing the boat, and it is the decision most people make last. Ha Long has the drama, Lan Ha has the swimming, Bai Tu Long has the silence. Sort this out first and the shortlist of boats writes itself.
Pick your waters
Ha Long Bay
The famous one. Nineteen hundred limestone islands, the most dramatic karst of the three bays, and by some distance the most traffic.
13 boats published20°47′N 107°02′ELan Ha Bay
The same limestone, quieter water, and beaches you would actually swim from. Administratively part of Cat Ba rather than Quang Ninh, which is why it feels different.
28 boats published21°04′N 107°25′EBai Tu Long Bay
North-east of Ha Long and far emptier. Fishing villages, quiet caves, and a realistic chance of anchoring within sight of no other cruise boat.
9 boats publishedOne practical point that catches people out: Ha Long boats mostly leave from the Ha Long International Cruise Port, while Lan Ha boats mostly leave from Tuan Chau Marina. The two piers are about twenty minutes apart, and drivers do occasionally take people to the wrong one. Name the pier when you arrange your own transfer.