The calculated distance (air line) between Eutin and Burg auf Fehmarn is approximately 31 miles respectively 50 kilometers.
By car or train, the actual journey to Burg auf Fehmarn is certainly longer, as only the direct route (as the crow flies) between Eutin and Burg auf Fehmarn has been calculated here.
Air line (approximately)
50 kilometers
27 nautical miles