Flying, except on a cheap flight where you are treated as "cattle" ...
Flying rox the bollox.
I think what makes us still uncomforteable is the fact that air and water are not places where Humans are meant to be. looking down and realizing you are NOT on terra firma (either in air or in water) always gives a mental kick, and a reminder to be alert.
It works for minutes - untill i fall asleep, smiling, listening to the turboprop or Jet engines.
Funny coincidence, i got a new machine days ago, and as i write this, on the second monitor is the FSX installer finishing its thing...
heres a shot of me...