Spatial Disorientation is always waiting to bite you when you least expect it in my opinion....
I've copped it once for about fifteen seconds - on a perfectly still winters day at Point Cook. Low Grey overcast, low light, lots of haze, and I took off on 17 straight out over grey water with no wind/waves. Guess what? Once over water, no anchored ships and no horizon!
It's a weird feeling, not knowing which way is up, but a quick glance at the AH and a look over the shoulder at land fixed it. Did a few circuits and watched the same thing try to happen to me each time.