Mate - the water that far south is pretty cold. We're not talking nippy here but seriously cold. I visited Ushuaia in 2004 and I wasn't tempted to kite at all. I was there in late Feb and there was still snow on the ground up behind the town. There are heaps of good reasons to visit the deep south but kiting isn't one of them. Go climb some glaciers or hike the southern Andes - its spectacular territory.

If you're over that way be sure to check out the Argentinian coastline further north and then head up to Brazil. Those coastlines would be far better I reckon. Warmer and more kite (& kiter) friendly.

(On the other hand - if you're a total mad-man perhaps you'd consider trying to be the first person to kite around Cape Horn - now that would be hardcore)