Which Assassin's Creed game introduced the ship-based naval exploration later expanded in Black Flag?

Assassin's Creed III introduced the ship-based naval exploration later expanded in Assassin's Creed IV: Black Flag.

Assassin's Creed III, released in 2012, added naval missions in which Connor commands a ship and fights in battles at sea. These sequences introduced sailing, wind management, naval artillery, boarding actions, and ship upgrades as major gameplay ideas within the series.

Assassin's Creed IV: Black Flag, released in 2013, made those mechanics central. Its protagonist, Edward Kenway, explores a large Caribbean world by ship, turning naval travel, piracy, and sea combat into the game's defining activities.

The distinction matters because many players first remember naval exploration from Black Flag. However, Black Flag expanded a system that Assassin's Creed III had already introduced. Assassin's Creed Rogue later developed the naval formula further with a Templar protagonist and a North Atlantic setting.