For the Halong City port, catch a bus going to "Hon Gai" which will take about 4 hours. From Hon Gai (Halong City) the ferry leaves at 1 or 1:30 PM and comes back at 6:30 AM (or at 6:15 AM in the summer) and takes around four hours. As of May 2012 the price is 70,000 dong for Vietnamese and 130,000 dong per person for foreigners. This route gives you a scenic boat ride through Bai Tu Long bay and drops you off at the port just south of Quan Lan village.
For the Cai Rong port, catch a bus going to Cua Ong and tell the staff you want to get off at "Cho Cua Ong" (Cua Ong market) and they will drop you off at an intersection in front of taxis that can take you to Cai Rong town about 12 km away. The trip will take 5-6 hours to get to this point. From Cai Rong port there is a ferry at 7 AM (or 6:30 AM in the summer) and 2 PM. Boats from Quan Lan going back to Cai Rong leave at 7 AM (or 6:30 AM in the summer) and 2 PM. The ferry takes two hours. There is a speed boat that makes the trip in 45 minutes that leaves at 7 AM, 8 AM, PM and 2 PM from Cai Rong for 140,000 dong per person. Return boats leave around similar times.
Ferry boats will drop you off at the port south of Quan Lan village while private chartered boats can drop people off at the northern port near Minh Chau.