Wait for the sub to appear. When it appears, get on the deck of the sub. It’s important that you step foot on the deck first, then move up the gang plank until you’re near the top. If you look to your right you should be lined up with the metal railing of the boat. When the sub starts moving, it should take you with it. There will be a split second where you clip through the railing of the boat and if you move forward in that split second then you’ll fall through the boat and be able to swim over to Nazgrim and turn in the quest.
![](https://i.ytimg.com/vi/Pceum9lTHCI/maxresdefault.jpg)