Ubisoft have released a Commentated Gameplay Walkthrough of Assassins Creed Black Flag. It lasts roughly 10 minutes and shows a variety of things that you will come across in the bigger than ever Assassins Creed open world.
The video starts out showing you how you can go under water diving to collect ship-wrecked treasure. It then takes you to a cave in order to show off it’s new stealth mechanics. The player is then whisked into a full-blown harpooning session with a shark.