Question: Hanakoa Valley is a hanging valley located on mile 6 of which trail that has been named one of the most beautiful, and dangerous, hikes in the world?
Context: Hanakoa Valley is a hanging valley along the Kalalau Trail along the Nā Pali Coast of the island of Kauai in the state of Hawaii.  Hanakoa has primitive camping via permit only.  It is located on mile 6 of the Kalalau Trail, often used as a resting destination for hikers completing the Kalalau Trail to Kalalau Valley.  Nearby Hanakoa Falls is accessible by an unmaintained trail. Sphinx Valley ( ) is a shallow hanging valley, 1 nautical mile (1.9 km) long, running northwest parallel to Columnar Valley and terminating just west of the summit of Table Mountain, at the northwest side of Royal Society Range, Victoria Land.  Named from the distinctive rock formations along its northwest wall, one of which is a particularly good likeness of the Egyptian Sphinx.  Named by Alan Sherwood, New Zealand Geological Survey party leader in the area, 1987-88. Ringer Valley is a hanging valley 6 mi long between Kuivinen Ridge and Stone Ridge in Saint Johns Range, Victoria Land.  The lower and middle portion of the valley is occupied by Ringer Glacier, which flows north to Miller Glacier; the upper (south) portion is mostly ice free.  It was named by the Advisory Committee on Antarctic Names in 2005 in association with Ringer Glacier and The Ringer. Lonesome Valley is a 23-mile (37 km) long valley located in central-north Yavapai County, Arizona; the valley is an extension southeastwards from Chino Valley (Arizona), the location of the Big Chino Wash, which becomes the Verde River at Paulden, Arizona; Paulden is located at the northwest terminus of Lonesome Valley.  A small sub-valley is located on the northeast perimeter of Chino Valley, Arizona, located in the center-northwest of Lonesome Valley.  The valley is named Little Chino Valley, and is the small valley link between Chino Valley, northwest, and Lonesome Valley, southeast. The Kalalau Trail is a trail along Nā Pali Coast of the island of Kauai in the state of Hawaii.  The trail runs approximately 11 mi along the island's north shore from Keʻ e Beach to the Kalalau Valley.  The trail has been named one of the most beautiful, and dangerous, hikes in the world. Cartwright Valley ( ) is a hanging valley that is for the most part free of ice, lying east of Mount Aeolus in the Olympus Range, Victoria Land.  It was named by the Advisory Committee on Antarctic Names (1997) after Keros Cartwright of the Illinois State Geological Survey, who made hydrogeological studies with Henry Harris in Victoria Valley, Wright Valley, and Taylor Valley during the Dry Valley Drilling Project; 1973–74, 1974–75, and 1975–76 seasons. Kellogg Valley ( ) is a high (1,400 m ) hanging valley, for the most part free of ice, between Mount Boreas and Mount Aeolus in the Olympus Range of Victoria Land, Antarctica.  The valley opens north to McKelvey Valley, 500 m below.  It was named by the Advisory Committee on Antarctic Names (1997) after husband and wife glacial geologists Thomas B. Kellogg and Davida E. Kellogg, of the Department of Geological Sciences and the Institute of Quaternary Studies at the University of Maine, who in several seasons over period 1976–90, collaborated in the study of the glacial history of the McMurdo Sound region, including field work on the McMurdo Ice Shelf, Ross Ice Shelf, in the Ross Sea, and the McMurdo Dry Valleys, the location of this valley. Albert Valley ( ) is a hanging valley between Conway Peak and Wendler Spur in the central Apocalypse Peaks of Victoria Land.  The valley opens north to Barwick Valley.  Named n 2005 by the Advisory Committee on Antarctic Names after Mary R. Albert, Cold Regions Research and Engineering Laboratory, Hanover, NH, who conducted field and laboratory research to characterize ice core, firn, and snow properties from Siple Dome, from the US-ITASE traverses of West Antarctica, and from East Antarctic megadunes, 1996-2003; Member, 2002- , Polar Research Board, National Academy of Sciences; Chair 2003- , U.S. National Committee for the International Polar Year, 2007-08. Mullins Valley ( ) is a four mile long valley located at 5,400 ft elevation in the McMurdo Dry Valleys.  It is one of the few dry valleys in the world to contain rock glaciers.  US Antarctic Program (USAP) research has dated the subsurface ice in Mullins Valley at 4 million years old making it among the oldest ice on earth.  United States Antarctic Program (USAP) research has also shown the rock glaciers in the valley to be analogous to the Arsia Mons region on Mars.  Named for Jerry L. Mullins, Physical Scientist, Director, Polar Programs, Antarctic and Arctic Program for United States Geological Survey (USGS), National Science Foundation Antarctic geophysical research, and U.S Scientific Committee (SCAR) delegate to SCAR SCAGI committee.  Appointed by the National Academy of Sciences, Polar Research Board.  His was responsible for Antarctic field research in the Transantarctic Mountains, McMurdo Dry Valleys, Shackleton Mountains, Beardmore Mountains, Antarctic Peninsula, Mount Siple, Amundsen-Scott South Pole station and at deep field research locations in West Antarctica.  His program conducted research in the disciplines of global positioning systems, geodesy, crustal motion, glacial geophysics, airborne geospatial systems, airborne geophysics, seismology, light radar (lidar), topographic mapping and he managed the USGS South Pole winter-over program from 1989 to 1994.  He was appointed by the National Academy of Sciences, Polar Research Board as a US delegate to the Scientific Committee on Antarctic Research Geosciences Standing Scientific Group from 1995–July 2012 and was appointed as a member of the Advisory Committee on Antarctic Names in 1994.  Mullins Valley appears in the Antarctic research literature, on the maps from the British expedition of Captain Scott and in aerial photographs from the United States expedition Operation Highjump by Admiral Byrd.  Mullins Valley, Mullins Lake, Mullins Glacier, and Mullins Geodetic Station, Antarctica are named for United States polar explorer and researcher Jerry L. Mullins. Papitashvili Valley ( ) is a hanging valley between Wendler Spur and Besson Spur in the Apocalypse Peaks of Victoria Land.  The valley opens north to Barwick Valley opposite Hourglass Lake and is ice free but for a glacier at the headwall.  Named after Vladimir O. Papitashvili, Space Physics Research Laboratory, University of Michigan, Ann Arbor, member of a joint US-Russian project to collect magnetometer data in the Mirny to Vostok Station area; four seasons, 1994-99; Program Manager for Aeronomy and Astrophysics, Office of Polar Programs, NSF, 2002- .
Answer: Kalalau Trail