In this guide, you will find the locations where you can get the Mysterious Pod in Fortnite. It will also let you know how you can get the chest from them.
The first thing you will need to do is head to the Stealthy Strongholds location and go to the top left side of this location, as shown in the map below.
After reaching there, you have to go through the river to find a very big tree. You will find your mysterious pod right next to this tree.
Now you will need to break its door to open it and grab the chest inside it. It will complete your first challenge of the Predator Challenges.