The event, held under the auspices of Croatian President Stjepan Mesic, was opened by his envoy, the Chief-of-Staff of the Armed Forces, General Josip Lucic.
The 22.5 kilometre race, which attracted some 50,000 local residents and visitors, will end in the southern port of Ploce.
The winners will be presented with awards, the main one being a 28-kilogram shield of Prince Domagoj.
Prince Domagoj, born in the Neretva River valley, ruled from around 864 to 876, successfully opposing the Venetian navy.