Fallout 76's Appalachia plays host to a number of nasty mutated beasties. Whether of the aquatic variety or not, carrying a sizeable harpoon gun, like the Kingfisher, around does provide a decent amount of protection against them.
Here's what you need to know about how to get the Kingfisher weapon in Fallout 76.
Fallout 76 Kingfisher
If you're looking to get your hands on Fallout 76's weekly Kingfisher weapon you're going to have to complete the, appropriately named, weekly challenge Go on a Fishing Expedition. It's worth noting that you'll have to hop into Survival mode to complete it.
You'll need to complete four tasks before you can impale mutated monsters with the Kingfisher: claim the Lakeside Cabins workshop, complete a quest or event in Cranberry Bog, kill an aquatic or semi-aquatic creature and cook a meal using meat from an aquatic creature.
The first task is pretty self-explanatory. Head on over to the Lakeside Cabins workshop and clear it of enemies using whichever gun you fancy the most. If you've a quest waiting to be completed in Cranberry Bog, now's the time to get to it. Otherwise, you're going to have to wait until an even marker pops up in the area and make your way towards it as fast as you can. Completing these two tasks puts you haflway towards obtaining the Fallout 76 Kingfisher.
If you're near the Lakeside Cabins workshop, you should be able to find a handful of mirelurks by walking a bit towards the north. However, you can kill just about any aquatic creature to complete the task. The mirelurks are a good choice simply because you can use their meat to complete the fourth and last task, earning you the Kingfisher weapon. Fallout 76's latest weekly weapon deals +30% damage to mirelurks and bugs, gives V.A.T.S. critical shots +50% damage and fills the V.A.T.S. critical meter 15% faster.