Which Assassin's Creed game was the first to let players sail freely through a large Caribbean open world?

Assassin's Creed IV: Black Flag was the first Assassin's Creed game to let players sail freely through a large Caribbean open world.

Released in 2013, Black Flag expanded the naval gameplay introduced in Assassin's Creed III into the central structure of the adventure. Edward Kenway uses the Jackdaw to travel between islands, approach ports, hunt sea creatures, find treasure, and attack or board other ships.

Assassin's Creed III included important naval missions, but its ships operated within specific mission scenarios rather than a comparable free-roaming Caribbean world. Black Flag made the sea itself a major explorable space and linked sailing, upgrades, commerce, and combat.

Rogue later reused and expanded many of these ideas in a North Atlantic setting, while Odyssey offered another large-scale maritime world in the Aegean Sea. Black Flag remains the series entry most directly identified with the Caribbean pirate setting.