High altitude & a bright sunny day equals overexposure on modern “automatic” digital cameras, the problem yet again is the light meter and how it is set to adjust exposure. The first thing to do is to check the ISO ASA settings and set them as low as possible 100 or 200. This effectively desensitizes the CCD sensor that records the image digitally. It is the same as using a film that is less sensitive to light. Traditionally using film in an older SLR you could “stop down” a couple of f-stops (which forced slight under exposure). Some digital cameras will still let you do this, but more now use an EV adjustment. One EV is roughly like each f-stop (it halves the light). To compensate for bright day/high altitude normally change EV to –1.0 or –2.0. Different cameras have different ways to set the EV compensation, but it is frequently available as via a combination of button, dials, sliders or discs so you don’t have to resort to the menu. So do yourself a favor, and read up how to use the EV setting from your camera’s manual today.
Some digital cameras have special “scene” modes and some have a even have Surf & Snow setting, (my Pentax has a snowman in front of something jagged with i assume are waves). The downside is this special scene modes will normally be menu selectable using a menu on the LCD screen and It is really bright so the LCD screen just about impossible to read!