One of the many commendations you can complete as you bury and dig up treasure is the Burying the Past commendation.
To complete this commendation, you must bury valuable treasures that were stolen from another crew. This requires that you bury one piece of treasure first touched by another crew.
To work on this, you will first need to get your hands on a piece of treasure that your crew did not discover.
Burying the Past Commendation
To complete this commendation, you can bury any piece of treasure discovered by another crew. As long as another crew touched the piece of treasure before your crew, it will count as stolen.
To get a stolen piece of treasure, you can, of course, steal it from another pirate crew. You can also be gifted the piece of treasure if you come across a friendly bunch of pirates.
The treasure you often find lying around Outposts such as Storage Crates will also count!
Once you have your stolen piece of treasure, simply bury it in any soft ground across the Sea of Thieves to complete the commendation.