What's the sand dunes rec area in SE CA / SW AZ?

[e9999]

while driving from Calexico to Yuma, I passed a large sand dunes ORV rec area, somewhere close to the border of the 2 states. Was evening and don't remember the name. Any idea what that was ? Seemed like hundreds of vehicles (weekend) incl. lots of campers.
thanks
Eric

 

[hammerhead]

Glamis and Gordons Well are in that neighborhood.