Used cat ba ventures in August with my parents. Unfortunately the weather wasnt great so we had to change our plans but the guys at cat ba ventures were really helpful and sorted it all out. Food on our junk boat was excellent and i was very pleased with the tour of cat ba and ha long bay. Kayaking was probably the highlight. Our guide was so good at pointing things out and without we wouldt have seen a Cat Ba Langer up close.
Definitely not the cheapest option on Cat Ba however and i'm sure you can get similar things very cheaply.