There are some pretty good reasons that this moderately challenging 3.3-mile loop is among the most popular hikes in Volcanoes National Park. With a descent through rain forest, it takes you down to a solidified lava lake in the Kīlauea Iki crater. And with a series of switchbacks, it brings you back up to several scenic overlooks. But we recommend getting an early start, because the parking lot tends to fill up fast.