Route: Mauna Loa (HI)

http://www.summitpost.org/mauna-loa-trail/235751

Gerad Dean briefly described the route for the Summit Trail (starting at around 6700' elevation):

During a recent trip to Hawaii (Big Island) I wanted to see if I could complete the Mauna Loa Summit Trail from car->summit->car in a day. The trail, from trailhead to summit, is about 19.5 miles in length and boasts approximately 7000’ elevation gain. It is a long, steady, and generally gradual climb. The trail, marked by ahu (rock cairns), is nearly entirely above tree line and makes its way across a stark landscape of recent lava flows. There is essentially no vegetation, making the entire trail exposed to the sun with very few shaded breaks. It also lacks any reliable source of fresh water, so I would need to be entirely self-sufficient on this day.

Another Variation is "Sea to Summit" (ascent only), about 54 miles.

Alyx Luck Barnett added the Short Summit variation: "The shortest route to the summit of Mauna Loa. This route isn't easy however, despite its short and commonly run/hiked length. What it lacks in miles it makes up in technical 'A'ā lava flow and steep dangerous climbing. Mauna Loa summit from the long side is gentle and slow, with discomfort due to exposure and time on feet. This route is a gut punch from the parking lot, but with guts can be done quickly. Don't fall however or you will be headed to the ER, whenever the helicopter finds you."