The calculated distance (air line) between Arenal and Acapulco de Juárez is approximately 186 miles respectively 299 kilometers.
By car or train, the actual journey to Acapulco de Juárez is certainly longer, as only the direct route (as the crow flies) between Arenal and Acapulco de Juárez has been calculated here.
Air line (approximately)
299 kilometers
162 nautical miles