The calculated distance (air line) between Giardini-Naxos and Siracusa is approximately 52 miles respectively 84 kilometers.
By car or train, the actual journey to Siracusa is certainly longer, as only the direct route (as the crow flies) between Giardini-Naxos and Siracusa has been calculated here.
Air line (approximately)
84 kilometers
45 nautical miles