Haleakala Highway is an asphalted road with a length of 37 miles, located in the Hawaiian Island of Maui. The road was completed in 1935 and climbs up the Pu'u'ula'ula (Red Hill), the tallest peak of Haleakalā mountains, at an elevation of 3.055m (10,023ft) above the sea level. It holds the world record for climbing to the highest elevation in the shortest distance of 38 miles.
The road is also known as Crater Road and Route 378. It’s a road mainly composed of switchbacks, open to the public (although parts of it are restricted) and is a well-maintained two-lane highway containing many blind turns and very steep dropoffs. Driving through the road you pass through as many ecological zones on a two hour drive to the summit of Haleakalā as you would on a journey from Mexico to Canada.
The road's winding design, providing stunning panoramic views, is very curvy and fun for a leisurely ride, so it pays to take it slow. It begins in the upcountry farming and flower-growing district of Kula at an elevation of 3,200 feet. It reaches the summit in 22 miles after 32 switchbacks, climbing an average grade of 6%. Note the last chance to buy food and gas is at Pukalani or Makawao.
The weather on this zone is harsh and highly unpredictable. A sudden drop in the temperature, even in summer, can trigger winter-like conditions. As you climb, notice that the temperature is dropping -- about 3 degrees F for each 1,000 feet in altitude. If it is 75 degrees near sea level, plan on about 45 degrees at the summit of Haleakala. Set your trip meter to zero at the junction of Routes 377 and 378.