In Assassin's Creed Valhalla, you can find special secrets called Treasures of Britain. Here, you will learn where to find the treasures located in Essexe.
This treasure can be found in the caves in the southern part of the city of Colcestre.
The treasure is located in the basement. To make it surface, you have to destroy the corks from wine barrels. Once the wine is spilled on the floor, the treasure will be lifted, and you'll be able to get it. This doesn't require any additional action.
You will receive an additional skill point for gaining the treasure.