Consider carrying a micro lens cloth and a simple nylon paintbrush for cleaning camera bodies, lenses and eyeglasses. Because summer days are so long, you will likely be taking pictures in bright light conditions. For capturing truer colors in your photos, carry ASA 100 slide and print film. For taking pictures in snowy conditions, nothing beats a hand held light meter for getting the most accurate light readings. Hand held meters really make a difference, especially when snow is present in the fore or background.
Snow is notorious for under exposing photos.
Carry sufficient amounts of film. You will be surprised how fast you can shoot pictures in areas such as Denali or Kenai Fjords National Park. Always bring double the amount you think you will need. For taking pictures on the water, a polarizing lens filter and lens hood will allow shooting right into the sun. Polarizers are also handy for removing reflections from nonmetallic surfaces, like glass or water.