Tsing Shan Monastery.
A beautiful monastery up the hill from Tuen Mun. It has several temples and other Buddhism related buildings, and below the main monastery many temples can be found scattered around the hillside. More information on Wikipedia.
The cache is a small container, containing log book. In weekends there will be quite some people walking by visiting the monastery or walking to or from Castle Peak, so bushwhack stealthily when searching for this cache!
Getting there.
The monastery can be reached by walking 30-40 minutes steep uphill from Tsing Wun LRT station in Tuen Mun, or by taxi.