The calculated distance (air line) between Smach Mean Chey and Sihanoukville is approximately 73 miles respectively 117 kilometers.
By car or train, the actual journey to Sihanoukville is certainly longer, as only the direct route (as the crow flies) between Smach Mean Chey and Sihanoukville has been calculated here.
Air line (approximately)
117 kilometers
63 nautical miles