The calculated distance (air line) between Montero and San Ignacio de Velasco is approximately 165 miles respectively 266 kilometers.
By car or train, the actual journey to San Ignacio de Velasco is certainly longer, as only the direct route (as the crow flies) between Montero and San Ignacio de Velasco has been calculated here.
Air line (approximately)
266 kilometers
143 nautical miles