View and/or walk the beautiful Buttercup Dunes when traveling on the I-8.
I found these amazing dunes when traveling from Phoenix to San Diego. These are a nice break from the 5+ hour drive. They are very picturesque and nice to walk on. I would advise to avoid the summer as I would imagine it would be uncomfortably hot.
When you are driving on the I-8 in either direction, you can take the Grey's Well Road exit to explore these dunes. Have fun and be safe, there are ATV's driving around. I heard you can also rent those in nearby towns to drive the dunes as well.