The Cheung Chau Bun Festival is around the Buddha's birthday. The whole island celebrates it and it's climax reach when there is a big procession on the Buddha's birthday. It has nothing to do with the buddha. It's only the last few years they decided to have the procession held on a public holiday so everyone can enjoy. Multi-storey tall bun towers, bakers busy at steaming buns, Chinese opera and taoist pray and ceremony.... you just have to experience it.
HK consists of a lot of little islands, some of which are vey nice and uncrowded! You can go hiking and biking on some of the islands, and some of the beaches are much nicer! You don't get the polluted air that you do on the main Island....so if you have time, go check it out....it's definitely worth the trip!
This island, about an hour's ferry ride from HK Island, is very charming. No motorized vehicles are allowed on this island, though bikes abound (and it's quite cheap to rent one for the day). The island is dumbell shaped, and is actually quite large, with substantive amounts of wild(ish) forests on both ends. The middle, where more people stay, is a dense collection of villages centred around the fishing life. Seafood there is amazing. There are a few temples scattered around, with one being quite old. A well visited route exists for hiking around the central part of the island, complete with a couple of caves and small beaches. The longest beach on the island is on the far side of the island (when you get off the ferry, head straight).
Hiking, biking, eating, birding, fishing, swimming.. there are lots you can do. But it's also good to just do it in a relaxing pace, taking in the sights and sounds of a somewhat traditional rural Chinese town.
A famous place for seafood. You can choose all the seafood by yourself and then go to any restaurants, they'll cook them base on your decisions. The restaurant will charge you for the cooking, it's around HKD30 per dish. Try to bargain and search before you buy the seafood because prices are different among shops.