Uneven, jagged lava makes for very challenging footing.
The Observatory Trail is also called the North Pit Trail on some maps. From the parking lot near the Mauna Loa Observatory (11,200 ft), ascend the lava field following occasional ahu lava cairns. Pass by collapsed lava tubes and cones, keeping an eye out for voclanic glass and other colored deposits.
Enjoy views north across the island to Mauna Kea. Some sections of this trail are comprised of an old, two-track, jeep road. Upon reaching the caldera rim, marvel at the immense size of the crater and the forces that created it. The Observatory Trail ends at a junction with the Mauna Loa Summit Trail
and Cabin Trail
Beware of altitude sickness, bring warm clothes, sun protection, excess water and food. Expect extreme and rapidly changeable weather. To avoid getting the bends, scuba divers should not ascend Mauna Loa within 24 hours of their last dive.