The calculated distance (air line) between Tuyên Quang and Cát Bà is approximately 140 miles respectively 226 kilometers.
By car or train, the actual journey to Cát Bà is certainly longer, as only the direct route (as the crow flies) between Tuyên Quang and Cát Bà has been calculated here.
Air line (approximately)
226 kilometers
122 nautical miles