With my level 81 character, I first got a new quest update once I read the book 'Deathbrand' (located all over the place). It gave me a map marker to the aforementioned Pirate's camp on the East side of the island. Once arriving there and taking out those thugs, I got the Treasure Map (located in your Misc inventory). Once looking at it, it updated the quest again 'look for treasure using the map' (or something like that). The rest of the quest is pretty basic - just look at the map and the boss chests are pretty much out in the open. The final reward is a barrow with plenty of loot. --- Video Game Console Library http://www.videogameconsolelibrary.com
The quest is lvl based (I can confirm 40+), though some have said they've managed to do it at 35.
I couldn't do it when my character was 17, reading the book did not work nor did going to the location (chest wasn't there). Read the book at 40+ and no problem, activated. --- We trained harder than you today, and we're gonna party harder than you tonight. Mint with the crew.