This hike is rated as moderate, but it was very easy. There is hardly any elevation gain and the switchbacks are long making what little you have to gain a breeze. Plenty of water along the trail to filter, or for your dog to drink. As noted by the previous review, lower red castle lake is picturesque but definitely not pristine. We camped in the site with the heart shaped rock. It was nice until we noticed all the human waste that was not properly buried. We had set up our tent not realizing till the next morning how close it was to utter grossness. Leave no trace is important. If your not sure what this requires look it up and please respect our wilderness.