Great day hike. I parked at the North McDowell access area. Probably want a 4 wheel drive to get there its a little rough and I didn't see anything but 4 wheel drive cars there. The hike was nice a little shorter. If you want to go a bit longer go past the thumb and down another ravine following the Tom's Thumb trail. I didn't follow it all the way because I ran out of time. Very cool once you get over the ridge, lots of saguaros etc. The caves are fun to explore at the thumb and its fun to see how far up you can get.