The following page contains the description of unlocking the bronze trophy Treasure Hunter in Shadow of the Tomb Raider. The achievement is awarded opening all the conquistador chests.
Conquistador Chests are one of the collectible secrets in Shadow of the Tomb Raider. An example of such chest is shown in the picture. Information about the location of the chests can be found in the chapter on secrets in our guide.
A very important piece of information is that you cannot open Conquistador Chests from the very beginning of the game, because you need a lockpick. Lara does not have this item and you can only acquire it in the Hidden City of Paititi.
You can get a lockpick by buying it from the merchant (shaman) Moraekah in the Hidden City. The easiest way to meet the woman is to complete the side quest Dice with the Dead, namely after receiving an job from Pisco the Dead to find other exiles. One of the persons you'll need to ask is the shaman Moraekah, whose location is shown in the pictures above. In addition to pushing the main quest forward, you can also trade with Moraekah in the aforementioned side quest.
Moraekah may change her location later in the game -more information on that can be found on the "Where to find merchant Moraekah?" page of our guide.
Lockpick is one of the items you can buy from Moraekah - it costs 2800 gold (see the picture). Lara will need only one lockpick, and she will never lose it.