Grendich Gamble is a GW2 jumping puzzle located in Diessa Plateau. This jumping puzzle doesn’t contain a chest, but it does have a rich silver vein at the top (as well as nets you an achievement, of course).
Start by heading to Blasted Moors waypoint.
You’ll be heading up this tower.
Most of the puzzle consists of walking up stairs, jumping on broken pieces of stone, and jumping on wooden beams. See the images below on where you should be jumping and you’ll be up at the top in no time. You will need to fight a veteran if you plan on mining the rich silver vein, but otherwise getting to the top will net you your achievement. Simply drop down to a safe spot if you don’t wish to fight.