Which Assassin's Creed game was the first to introduce playable naval missions?

Assassin's Creed III was the first Assassin's Creed game to introduce playable naval missions.

Released in 2012, the game gave players command of the Aquila, a sailing ship used by Connor Kenway. Naval sequences included steering, managing speed, positioning the ship, and firing cannons during battles in the Atlantic Ocean.

The naval system was a significant expansion of the series rather than a minor side activity. Its popularity helped inspire Assassin's Creed IV: Black Flag, which made ship travel, exploration, and sea combat the central focus of its gameplay.

A common mix-up is to name Black Flag because it is the franchise's best-known naval game. However, Black Flag followed Assassin's Creed III by a year. Assassin's Creed III is set during the American Revolution and combines frontier exploration, cities, and maritime missions.