on river right @ Tabyago riffle
I'll give it a shot: About 9 miles below Sand Wash is the first riffle after hours of flat water. Tabyago riffle on the maps (Belknap). At higher flows 10,000 + there really isn't a riffle, just faster water. With attention to the map you should be able to key in on the location. It's about a 1 mile+ below the big bend at Gold Hole, below the big island and upriver of where the river makes a hard right below steep cliffs. Tabyago canyon also comes in on river Left. Look for any landings on the right in the riffle. There is a faint bench trail that leads upriver a bit. The chest and other old items are in a natural "cave" created by two large boulders on the hillside. Good Luck!