A couple to start:
That feeling when your ears pop on the descent and all of a sudden you can hear the full bassy glory of the wind and the streams and the waterfalls. I'm sure the pressure differential is not too significant but I'm also sure it's not just me that this happens to. A small reminder that you're pushing yourself, if only a bit, into the realm of the birds and the aeroplanes

Also that time of year when only the very highest summits are pure shimmering white, so you can spot a barely overtopping munro in a panorama which you never noticed it in before
