The Spirit Vessel is a small object that you need to collect in order to complete a mission in the new Dark Jonesy questline. However, this is a two part challenge.
You need to use a Shadow Stone first before you can collect the Spirit Vessel. That being said, here's a guide to help you collect a Shadow Stone and then the Spirit Vessel.
Where to recover the Spirit Vessel in Fortnite
There are two locations where you can actually find the Spirit Vessel in Fortnite. And thankfully enough, both these locations are close to Shadow Stone clusters as well.
Although you do have a good amount of time before the effect of a Shadow Stone wears off, it still does help to have both mission objectives close by.
That's being said, here's a quick run down of what you need to do.
First off, the two Fortnite Spirit Vessels are located at Dirty Docks and Weeping Woods. The Fortnite Spirit Vessel locations are marked on the map below.
In order to get to them, you need to land at the Crash Sites that are close to these two places. Once you've made it to the Crash Sites, you need to interact with a Shadow Stone and then make your way to these vessels.
The Spirit Vessel at Dirty Docks is located close to a large blue pylon on top of a small hill. So interact with the Shadow Stones at this place and then make your way up the hill to get to this place.
The Spirit Vessel at Weeping Woods is located close to Grim Fable. And thankfully enough, you will find a small Shadow Stone cluster here too.
Interestingly enough, all this will be marked on your map as well. You will see a small exclamation mark pop up on your minimap once you're close to the location.
Personally, I'd recommend visiting the Spirit Vessel at Weeping Woods because the Shadow Stone cluster is closer to it.
Have fun!