Mauna Loa descent
Distance: 27.76 km
Elevation Gain: 10 m
Elevation Loss: 1371 m
Difficulty:
85 (Easy)
FIETS Index: 0.00 FIETS
Avg Grade: -4.90 %
Max cat climb: 5
Min elevation: 1998 m
Max elevation: 3359 m
Ride Category:
Flat
By many accounts the longest bike climb in the world ends high on Mauna Loa, on the Island of Hawaii, USA: about 100 km from Waikoloa on the coast up to the observatory. Mauna Loa, the “long mountain”, is the largest active volcano on Earth. It covers about half of the island and rises to 4,169 metres. It has erupted 34 times since 1843, most recently in November 2022, after 38 years of quiet, its longest rest on record. Across the saddle rises its neighbour Mauna Kea, the tallest mountain on Earth when measured from its base on the sea floor.
This ride descends the Mauna Loa Observatory Road, a single-lane road across the lava fields, from just below the observatory almost all the way to the Saddle Road. Since March 1958 the observatory has measured the carbon dioxide in the air; its record, the Keeling Curve, was the first to show CO2 rising year after year. In 2022 the eruption sent lava across this very road, burying almost 2 km of it under up to 9 metres of rock. A temporary road over the new flow was completed in March 2026, so part of this descent now crosses rock only a few years old.
