The calculated distance (air line) between Yuen Long and Tsz Wan Shan is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Tsz Wan Shan is certainly longer, as only the direct route (as the crow flies) between Yuen Long and Tsz Wan Shan has been calculated here.
Air line (approximately)
21 kilometers
11 nautical miles