The calculated distance (air line) between Burg auf Fehmarn and Heiligenhafen is approximately 10 miles respectively 16 kilometers.
By car or train, the actual journey to Heiligenhafen is certainly longer, as only the direct route (as the crow flies) between Burg auf Fehmarn and Heiligenhafen has been calculated here.
Air line (approximately)
16 kilometers
9 nautical miles