Recently had a day off, and finally tried out a hike I've been meaning to do for ages. Popolopen is NOT a beginner hike; there are some steep parts and several rock scramble areas. The official parking is in a lot off 9W, but there is a sneaky two- or three-car-lot about halfway up the trail. I didn't have time to do the full hike, so I parked in the sneaky lot and did an early morning hike, coffee in hand. I wouldn't recommend scrambling some of those rocks without a backpack to put your items in... it only worked because I rock climb on the regular and could figure out some funky shapes to contort my body into with the one hand available. Anyway, the views when you get to the top are spectacular, and well worth the effort!