Do not ever book with Syrena Cruise and nerve book through Trip Advisor or Viator for the following reasons:
1. Bother the Syrena and the Trip Advisor/Viator LIED with impunity about absolutely everything, such as visit to a floating village needed in the price of US$170 per person for one night cruise, but there was none; kayaking included in price, but when we arrived at the place where kayaking is offered, Syrena guide told us to pay US$ 15 per person; they promised in an email confirmation that the food on board will include gluten-free options, but there were none there and when we asked, they specifically told us they don't have such food; BTW, the food in general can be best described as substandard of all substandards; there was a promise on the Trip Advisor ad that there is a gym and swimming pool on board, but there were not even basics present, such as toilet paper, let alone gym and swimming pool.
Second, the staff were exceptionally rude to us especially when we asked for gluten-free food and kayak, even when I asked for napkins the waiter angrily went and brought it as if I requested something special. The staff did not allow us to get food from the buffet 5 min before exact time of meal, but the previous day they allowed other 8 passengers to take all food in advance so it was nothing left for us. I requested a fresh orange juice in evening for dinner, they told me they run out of it, but oranges mysteriously appeared in the morning although the boat never touched the coast, but stayed in the bay waters all night. The manager was also rude when I asked for gluten-free food, promised kayaking, and when I complained about her rude staff. The boat itself is small old and falling apart. Rooms are tiny . No activities were offered. This is maximum a US$50 cruise, and nowhere close to 170 per person, which is what we paid . The staff ignored me when I wanted to order juice. The boat itself was stinking of gasoline all the time . Rip off of foreign tourists.

Well worth the money. Well organised and had a very enjoyable stay. The only damper was perhaps the long wait for the shuttle bus 1.5 hours after the cruise had ended.

The AC in the bus to Ha Long Bay was extremely cold. We were offered a bottle of water for the bus drive and we were only for people in it so it was comfortable.
Boat was good but nothing special, if you are taller than 180cm your head will touch the ceiling while having a shower. The only separation between the room and the toilet was a curtain.
Other boats around us had music in the evening and ours, nothing much going on... the only nice activity they did was the fresh spring roll cooking lesson.
Dinner was very yummy and food was good in general. The cocktails during happy hour were nice.
Their English was very basic and it was difficult to understand the explanations during the caves visit.
Once the cruise was over, they kept us in the boat with nothing to do, waiting for almost 2 hours for the pick up to go back to Hanoi, extremely long time. No water was offered this time.

Very hospital crew and really enjoy the trip. Food was good too.