Wicked stuff, found this link there......
http://walrus.wr.usgs.gov/pacmaps/sd-fly.html
It is movies of flyby's in the canyons. I had visions of dropping a line down these canyons but after looking at them I don't believe there's a reel that can handle the volume or the yak that could carry a fully loaded reel.
I'd love to know what is down there.