You need a variety of WARM layers. AND a lightweight lined nylon type jacket, key is quick drying. Take sweatshirts, turtlenecks, tshirts. Knit hat, gloves, 2 pair of walking shoes, rain gear. I never take jeans- too bulky, tend to get and stay damp and take forever to dry. For me lined and unline wind pants are perfect. I also always do my laundry off ship in Skagway - can be done in a little over an hour with their fast propane dryers- never mind the great conversations I have gotten in to. You can alway head to the Red Onion for a fast drink and return. Yes bring a tank top and shorts- there can be that much of a range. But most people are underprepared and it will greatly affect your trip.