The calculated distance (air line) between Tuen Mun San Hui and Sai Kung is approximately 19 miles respectively 30 kilometers.
By car or train, the actual journey to Sai Kung is certainly longer, as only the direct route (as the crow flies) between Tuen Mun San Hui and Sai Kung has been calculated here.
Air line (approximately)
30 kilometers
16 nautical miles