The calculated distance (air line) between Plön and Timmendorfer Strand is approximately 18 miles respectively 30 kilometers.
By car or train, the actual journey to Timmendorfer Strand is certainly longer, as only the direct route (as the crow flies) between Plön and Timmendorfer Strand has been calculated here.
Air line (approximately)
30 kilometers
16 nautical miles