The calculated distance (air line) between Santo Tomás La Unión and Amatitlán is approximately 53 miles respectively 85 kilometers.
By car or train, the actual journey to Amatitlán is certainly longer, as only the direct route (as the crow flies) between Santo Tomás La Unión and Amatitlán has been calculated here.
Air line (approximately)
85 kilometers
46 nautical miles