Starting from the parking area, descend gradually at first until reaching the western rim of Haleakala crater and the terminus of the Supply Trail
. Continue straight at the intersection where endless tight switchbacks cut down the steep cliff with significant change in elevation. From here you'll see a huge valley to the north (Ko'olau Gap). Expect loose lava rock, shrubby vegetation and little shade. Next up is an rugged cliff with spectacular views of the valley and coastline way below.
When you reach the crater floor, enjoy a brief respite on level ground before climbing again to the Holua Cabin. Overnight stays at the cabin and campground require a permit but there is a pit toilet available. The cabin is situated among native shrubs which have colonized the lava flows. Keep an eye out for the nearly extinct Hawaiian petrel in this area.
Continue across the crater floor over sandy, rolling terrain that generally climbs towards the multicolored cinder cones in the distance. Along the way, you'll intersect with the Silversword Loop
. This worthwhile detour does not add any real mileage, so you might as well visit this concentration of rare silversword plants. After rejoining the main Halemau'u Trail, crest a ridge and traverse an impressively barren, black stretch of newer lava. The trail surface is deeper sand/dirt and slow going. Other highlights along the route include the Bottomless Pit and Pele's Paint Pot- an ashy, technicolor landscape created by the minerals found in the lava.
Upon reaching the crater's large inner cinder cones, the Halemau'u Trail makes multiple junctions with the (roughly north-south) Connector Trails A-F which link the Halemau'u Trail to the Sliding Sands Trail. Any number of loops can be created by using these connectors. Continue downhill eastwards along the Halemau'u Trail to where the Sliding Sands Trail ends. Stay on the Halemau'u Trail and cross patches of smooth lava making for much easier travel. Then approach the steep hillsides through scrubby, dense vegetation and grassy fields. The Halemau'u Trail ends at a 3-way intersection with the Kaupo Trail
(to the south) and the Lau'ulu Trail (to the east).
Heed the warnings and be prepared for cold and unpredictable weather. Also, be aware that the high altitude will cause dehydration and fatigue much faster than at sea-level. As of this writing, no food is available for purchase inside the park, so bring your own.
Hawaiian petrel ('Ua'u), nene, silverswords.