Fallout 4's Far Harbor DLC is out today, but to access it you need to do a bit of this and that. Thankfully, Eurogamer's Ian Higton has worked it all out and created a cool little video guide for your viewing pleasure.
There may be spoilers ahead.
To get going, you need to have completed the quest, Getting a Clue, from the base game. This is the one where you and companion Nick Valentine break into and search Kellogg's house in Diamond City.
If you've already done that, when you load up a save your Pip-Boy will pick up a signal from Valentine's Detective Agency. Tune into the radio station, then make your way to the Agency in Diamond City.
There you'll be told of a missing persons case. You need to head up to the Nakano Residence, situated in the top right-hand corner of the map in a brand new area that was previously inaccessible.
You have to do some detective work for Kenji Nakano, a new NPC, before he'll let you use your boat to travel to Far Harbor.
But! Before you head out, be sure to bring Nick along as your companion. You'll get more on his backstory if he's around when you talk to people on the island.