We got to play Assassin's Creed 4: Black Flag's co-op modes in Annecy earlier this month. Take a look at Discovery and Unleashed in Sam's edit below.
For more details on the modes you're seeing here, read this report. Assassin's Creed 4: Black Flag is themed on pirates and set in the Caribbean. It releases this autumn for 360, PS3, Xbox One, PS4, Wii U and PC.