If you find yourself in Hong Kong and are eager to take a ferry to an outlying island, a trek to Lamma Island is definitely worth the ferry fare.  You can rent a bike from one of the local bike shops and explore the paths (bonus: no cars on the island!).  Have a bite to eat at the Bookworm Cafe...reflect at one of the small temples...go to Power Station Beach for Saturday beach volley ball, or if you are lucky, a beach rave at night.  Take in the atmosphere, not the view of the power station towers :)