Know Before You Go
This is a very remote area of Death valley and you are on your own with no services for close to 100 miles. You must plan ahead with a high ground clearance 4x4 vehicle, plently of water, fuel, food, and proper clothes. Also check with the park service for road conditions, weather, and backcountry maps of the area. Don't attempt this road in hot weather or on your own, it's best traveled with other vehicles.
The bathtub full of blue marbles is hidden in plain sight to those on Steele Pass going southbound, as they're looking right at it if they know where to look. It's about 100+ yards off the road in the canyon wash. You can look right down on it from the closed road that branches off at the summit, the one that climbs into the Last Chance Range. Please leave these wonders of the desert for others explorers to discover. And hey, why not plan ahead and bring your blue marbles to add to the tub. When you have lost all your marbles then you are a true desert rat.