It really depends on what form of skiing they do. If they are back bowl mountain skiers, I do not know exactly, but it is fast by skiing standards. In the Olympics, there's the downhill races. they may reach 95 mph depending on the course. There is also a type of skiing called speed skiing where people lock themselves in a nearly immobilizing suit and bomb down grooves straight down a steep mountain slope. In this, people have exceeded 150 mph. A crash in this could easily be deadly.
A ski-doo goes 50-60 km.
about 40mph
you go about 70-90 mph
about 60 k/ph
GP Class Stand Up skis are running in excess of 70mph and GP Class Runabouts are we into the 90's... Now THATS fast on a jet ski!
110-130km
of course it does! SKI FAST - HAVE A BLAST!
about 30 mph
45-50 mph
It will run around a 100 mph
65 mph
35-40ish