The calculated distance (air line) between Burg auf Fehmarn and Travemünde is approximately 35 miles respectively 57 kilometers.
By car or train, the actual journey to Travemünde is certainly longer, as only the direct route (as the crow flies) between Burg auf Fehmarn and Travemünde has been calculated here.
Air line (approximately)
57 kilometers
30 nautical miles