First off, pack layers of clothing. The weather up there can change in a heartbeat, so having thermal shirts, fleece jackets, and a good waterproof jacket will keep you comfortable no matter what. A good pair of binoculars is a must, you don't want to miss spotting whales or eagles. Finally, make sure you have waterproof footwear. Whether you're exploring glaciers or just walking around port towns, you'll want to keep your feet dry.