The Slytherin Blocs is a small and accessible area (from the drop off point) that is home to a number of fine low- to mid-grade problems. The northerly aspect and ease of access makes it a good spot for a quick afternoon session.
The Slytherin Blocs are located on the northern side of Kai Kung Leng, near the Ngau Tam Mei Fresh Water Service Reservoir. Access will require either a taxi ride or a car to get you to the bend in the road / stream just east of the Ngau Tam Mei Service Reservoir (22.468633, 114.074353). From the small clearing, follow the slope maintenance staircase to the left of the stream (looking up hill)a short way before breaking left along a berm. This will bring you to a dirt trail that weaves up the hill to eventually reach a small outcrop. Follow the trail right at this point and scramble over and around some blocs to reach the bouldering area itself. The approach takes less than 10 minutes from the road.