Hong Kong (one day at sea away from Keelung) and Okinawa (some ships make the crossing overnight) are often the ports that you have either been to or are going to next.
My friends often ask me for advice on 'what to do' on their own for a few days in Hong Kong in conjunction with the cruise. Well, around the time of the establishment of the HK Special Administrative Region, we lived in Happy Valley, on a 32nd floor with a view of the racecourse of the Hong Kong Jockey Club. We still visit and have good friends in Hong Kong, and over the years we kept notes of where to go.
So here is a map to help you on the way, showing you popular places on Hong Kong island, Kowloon, the New Territories and even a quick hydrofoil trip to Macau's casinos. Even though your ship may be docked at Ocean terminal, do take the "Star" Ferry across to Hong Kong island from Kowloon to Central or Wanchai, or take one of the one hour harbor cruises. From the ferry at Central pier 5 take bus 15C to the Peak Tram terminus.
You can use the MTR metro, bus, harbor ferry and double-decker tram. Buy an Octopus card at the station or convenience store. There is a special tourist souvenir edition at HK$ 39 to keep, or a regular one with HK$ 50 deposit. You add value and can get a full refund at the last station. It is a smart card (just swipe it), so you can pay with it for many other things too.
Let me know if you're missing or have discovered anything?