The road ends at a cinder hill called Puʻu ʻUlaʻula — Red Hill — and at 10,023 feet it is the highest ground on Maui. A low glass-walled observation building sits on top of it, which matters more than it sounds like it should: the wind up here is constant and cold, and being able to watch sunrise through glass rather than into a gale is the difference between staying an hour and staying ten minutes.
What you see from the rim depends entirely on the cloud. On the ordinary day, the trade-wind inversion caps out somewhere around 6,000 to 7,000 feet, which puts a flat white floor below you and nothing but sky above. Mauna Kea and Mauna Loa stand out of it across the ʻAlenuihāhā Channel, 80-odd miles away on Hawaiʻi Island, and on clear mornings you can pick out the observatory domes on Mauna Kea's summit as white specks. Turn the other way and the island of Lānaʻi and the long ridge of Molokaʻi sit on the horizon. Turn inward and the view is the crater: 2,600 feet down to a floor of cinder cones in rust and ash-grey, with nothing growing on it.
Two overlooks on the way up are worth the stop and get skipped by everyone racing the dark. Leleiwi, around 8,800 feet, looks into the crater from the north side and is the classic spot for the Brocken spectre, where your own shadow appears projected on the cloud below you inside a ring of colour. Kalahaku, higher up, has a silversword enclosure and can only be entered on the way down — there is no left turn into it on the ascent.
Adjacent to the summit, and closed to the public, is the cluster of research domes locals call Science City: Air Force space-surveillance telescopes, University of Hawaiʻi instruments, and the Daniel K. Inouye Solar Telescope, the largest solar telescope in the world. You will photograph them by accident from the summit and you cannot visit them.
This is a sacred summit in Hawaiian tradition, not only a viewpoint. Stay on the paths, take nothing, leave nothing, and do not build rock stacks.