Suncreen is even more important at high altitude. Look for sunscreens with a good UVA blocker like Mexoryl 3%, zinc or titanium 5-10%. UVA becomes more intense at altitude. It's a longer wavelength of UV radiation, and it damages your collagen and your collagen-making cells more because it penetrates more deeply, causing wrinkles.

Here's to a skin healthy holidays!

For a good sunscreen with mexoryl, try La Roche-Posay Anthelios 40.  I know that some of the customer reviews at SkinCareRx.com are not that great, but this is a good sunscreen.

For a good zinc-based sunscreen, try SkinMedica Environmental Defense Sunscreen SPF 30.  This goes on just a bit white, but you can rub it in.  And you want your skin protected at altitude.

Another good mineral-based sunscreen is Fallene CoTZ SPF 58.  Great mineral protection, with a slight tint so it doesn't make you white, and no fragances or chemical blockers.