We booked a trip with Blue Swimmer Adventures after seeing them listed in the Lonely Planet and corresponded with them via email prior to our arrival in Vietnam. Everything went as they told us it would - they sent someone to our hotel in Hanoi to deliver our bus/boat tickets and to give us instructions. The bus/boat/bus trip to Cat Ba Island was straightforward enough - somebody just shuffles you on to the next mode of transport. Our guide Henry and another guy on a motorbike met us off the bus and drove us to the Blue Swimmer office, where we settled the remainder of our payment and ate lunch at a nearby restaurant. We then took a boat to "base camp", which is collection of cabins/huts and a restaurant on an island. We stayed in a bamboo hut, which was basic but clean. (It might be advisable to upgrade to a cabin at the time of booking). I think the different tour companies 'rent' space here when required as the other people seemed to be with other tour groups. We spent that afternoon kayaking around Lan Ha Bay, which is strikingly beautiful and apparently less crowded than Halong Bay. The kayaks provided by Blue Swimmer were good (and they appeared to be better than the kayaks provided by other tour groups, from what I could tell by passing other kayakers).
The second day we were based from the junk boat. It was just the two of us, plus our guide, a cook, and the boat driver. (Three personal staff - great value for money!) We spent the day kayaking and swimming and spent that night on the boat.
The third day, we docked at Cat Ba island, where we cycled to a small village at the base of the highest peak on the island, which we subsequently climbed (nothing too strenous, took about 45 minutes) for fantastic views across the bay. We had a nice lunch in Viet Hai village after we came back down.
Henry, our guide, was excellent. He was very friendly, genuine, attentive, and knowledgeable.
The food that was provided for us on the boat was excellent - usually a selection of seafood, meat, tofu, vegetables and rice. It was impressive that the cook could rustle this up from his tiny little kitchen on the boat.
It should be noted that the standard of accommodation on the boat was basic (but clean) - it was fine for us, but just a warning for those who prefer more luxurious accommodation.
All in all, we both really enjoyed our trip, and would highly recommend Lan Ha Bay as a destination, as well as Blue Swimmer adventures.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.