Criptograma Chests are new to the Far Cry series. These new collectibles require you to search for and collect two Criptograma Charts to unlock them. One of these chests resides in the northern section of Ida’s Refuge in the Aguas Lindas region. Take a look at the map below for reference.
When you arrive in the small town, find a dock with a ladder leading up to a balcony. The Criptograma Chest is on the balcony. The arrow points to an island across a small bit of water. You can swim or take a boat over to the island.
When you reach the island, make your way to the top of the cliff near the beach. At the top, you will find the Criptograma Chart on the rocks with an arrow pointing to the next island.
Instead of being on the island, the second Criptograma Chart is found underwater. Find the destroyed dock on the second island. Dive under the water in that area, and you will find the Criptograma Chart on a piece of blue wood next to a large coral.
Now that you have retrieved both of the Criptograma Charts, head back to the chest and unlock it to gain your reward.