The calculated distance (air line) between Santiago Atitlán and Amatitlán is approximately 41 miles respectively 66 kilometers.
By car or train, the actual journey to Amatitlán is certainly longer, as only the direct route (as the crow flies) between Santiago Atitlán and Amatitlán has been calculated here.
Air line (approximately)
66 kilometers
36 nautical miles