Looking North across the Big Island's saddle
at Mauna Kea (which was about on the centerline of this eclipse).
Note how the moon's shadow first drops down from above and then withdraws
to the right in this sequence.
Just after start of totality.
The horizon is bright because we are looking out past the Northern limit
of totality. The knot of clouds in the distance is on top of Haleakala,
the highest point on the island of Maui, which was just outside the path
30 seconds after totality.
The umbra is clearly visible as a dark ellipse in the sky below
and to the left of the sun (to the left because Mauna Loa was well
South of the centerline).
I believe the shadow was so clearly visible that day because it was being
projected on Pinatubo dust high in the atmosphere.