I finally found a sunken shipwreck with a treasure chest and raised it to the surface! Nothing in ArcheAge can be done without maximum risk so naturally you can't just open the treasure on the ocean floor. First you have to bring it up with a recovery bag (that costs money and skill to craft) and then sit out in the open water while a bar fills to pry into it.

This time I didn't get too lucky and only found some mysterious tattered quill pens that no one on the Auction House is hot to pay for. But I know how salvaging works and love going out to sea and exploring the depths. More treasure will be found!