Microsoft did a nice in-depth look at Rare's upcoming swashbuckler, Sea of Thieves.
In Sea of Thieves, you dive down to the bottom of the sea, swimming with sharks in search of treasure and then bringing it back to the surface to your ship. As soon as you've got loaded up with booty, however, you become a target for other players.
As well as scouring the seabed, you can track down treasure chests by solving the riddle and locating the spot it's buried on a tropical island:
You can even co-op shovel. That's good shovelling, Rare.
Riddle solved and treasure found, the players make their escape, chased by skeletons and covered by cannon fire from their own ship.
Back on ship and sailing through the storm, the players come under attack from another ship and are boarded by vicious nefarious thieving pirates.
I can't wait for Sea of Thieves, it looks marvellous.