It's all lava, every single bit of it. It goes on forever. It is diabolical. It is long. It is a mountain. It is a long mountain. It is Mauna Loa.
The dark terrain is the awful a'a lava: so hard to walk through. The lighter terrain is smooth pahoehoe (the lava in the foreground).
Here we have the Observatory Trail-North Pit Trail/Summit Trail at around 13,200 ft. This route from the weather observatory is the quickest way up to the top (12 miles round trip). It took us roughly 6 hours round trip.