There are 7 exploration chests in Miska. You can either find this during your Miska quest or you can do it after you’ve completed the quest. I would suggest after the quest so you don’t hold your teammates behind. Alternatively, go alone and roam around as you like.
1st Chest Location: Evil Lure
You will find the chest on top of the bus. To climb on it, place your ammo box towards the edge (picture below) of the red car next to it to gain better leverage. Then climb onto the ammo box and jump onto the bus to get the chest.
2nd Chest Location: Disciple’s Defense
This is the same building Frida enters during Miska quest. When you enter the building, you will see a stage towards your left and the auditorium seats on the left. The chest can appear either at the boxes on the stages or at the corner right-hand side of the room.
3rd Chest Location: April’s Prank (Gazebo)
This is at the broken gazebo in the middle of the open area. You can see the broken pillars at the gazebo. Place your ammo box on the half broken pillar. Jump onto the ammo box and further jump to the top of the gazebo to get the chest.
4th Chest Location: A Book’s Golden Knowledge (Library)
This is the library area. The chest is located on the 1st floor of the library on top of the bookshelf. It can be at either side of the wing. If you don’t find this on the right wing of the building, go to the left wing.
5th Chest Location: Refugee’s Unlawful Possession (Basement)
You will see a pathway with pillars on its both side as you exit the library on the right wing. This path will lead you to the basement. Once you’re down at the basement, you can find the chest in a corner or next to the stairs. Look around the area if you don’t at first find it.
6th Chest Location: The Priest’s Collectibles
This is located in the building where you save the first student. Inside the room where you save the student, you will see an altar where you can find the chest right behind it. If you can’t find it here, it’s in another room. As you enter the building, go forward and instead of entering the room with altar, turn left then turn right and you should be able to find the chest in the room located on the other end of the building.
7th Chest Location: Smuggled Goods
The location of the chest here can vary as well. This is where you started when you arrive in Miska. I have found the chest on top of the truck or on top of the tent. If you see the chest on the truck, you can place ammo box or barricade to jump on the truck.