The calculated distance (air line) between Marske-by-the-Sea and Birkenhead is approximately 116 miles respectively 186 kilometers.
By car or train, the actual journey to Birkenhead is certainly longer, as only the direct route (as the crow flies) between Marske-by-the-Sea and Birkenhead has been calculated here.
Air line (approximately)
186 kilometers
101 nautical miles