The calculated distance (air line) between Ikšķile and Daugavgrīva is approximately 23 miles respectively 36 kilometers.
By car or train, the actual journey to Daugavgrīva is certainly longer, as only the direct route (as the crow flies) between Ikšķile and Daugavgrīva has been calculated here.
Air line (approximately)
36 kilometers
20 nautical miles