This locked chest is the fourth of Valle De Oro's four Criptograma Chests, hidden in the Balaceras area. Find its two Criptograma Charts and it opens to give you a piece of unique gear.
Head south of Feroza in Balaceras to a construction site full of shipping containers. The chest is close to a greenhouse with a water tank.
The chest stays locked until you have both of its charts. Look for Guerrilla Sigils, the guerrilla markings painted near the chest, and follow them to each Criptograma Chart. Once you have both charts, go back to the chest and open it.
Inside is the Fuego Mitts MK II. The two charts you used are also added to your Criptograma Charts collection, so every chest you open moves both lists forward.
Image: UbisoftCriptograma Box 1 - Barrial
This locked chest is the first of Valle De Oro's four Criptograma Chests, hidden in the Barrial area. Find its two Criptograma Charts and it opens to give you a piece of unique gear.
Criptograma Box 2 - Cruz del Salvador
This locked chest is the second of Valle De Oro's four Criptograma Chests, hidden in the Cruz del Salvador area. Find its two Criptograma Charts and it opens to give you a piece of unique gear.
Criptograma Box 3 - Noventarmas
This locked chest is the third of Valle De Oro's four Criptograma Chests, hidden in the Noventarmas area. Find its two Criptograma Charts and it opens to give you a piece of unique gear.
Image: UbisoftCriptograma Charts
Criptograma Charts are the coded symbol sheets that open Criptograma Chests. Every chest needs two of its own, so you hunt down 30 charts in all to empty the 15 chests on Yara.