The older, western volcano has eroded considerably, forming the peaks of the West Maui Mountains (in Hawaiian, Mauna Kahalawai). Puʻu Kukui is the highest, at . The larger, younger volcano to the east, Haleakalā, rises to above sea level, and measures from seafloor to summit. The eastern flanks of both volcanoes are cut by deeply incised valleys and steep-sided ravines that run downslope to the rocky, windswept shoreline. The isthmus was formed by sandy erosional deposits.
The older western volcano has eroded considerably forming the peaks of the West Maui Mountains (in Hawaiian Mauna Kahalawai) Puʻu Kukui is the highest at  The larger younger volcano to the east Haleakalā rises to above sea level and measures from seafloor to summit The eastern flanks of both volcanoes are cut by deeply incised valleys and steep-sided ravines that run downslope to the rocky windswept shoreline The isthmus was formed by sandy erosional deposits