... Celestial Navigation

I'm studying it, online course materials, with the help of a friend who is experienced with it.

Probably not too much practical use for me, since I've never done an ocean voyage of any kind, much less tried to navigate one (they probably all use GPS now anyways, with Cel Nav only as a backup).

Still, it's fun to learn! Exercise the brain learning new stuff.

Now, I just need to find myself a Sextant Shop. Those seem pretty rare here in Colorado...