break all the "T" shaped tombstones. there are 3 treasure chest like this.
1 at the beginning, break all the fire hydrants 1 at the choking grounds, break all the "T" tombstones 1 at the Twilight Cathedral, light all the torches.
also there is a treasure chest icon in the Drowned Pass (when you have Fury's embrace) that is confirmed to be a glitch and is merely an icon on the mini map and nothing more. --- We each play out the parts Fate has written for us. Free will is an Illusion. - Kain