When the ship’s captain announces a whale breaching up ahead or a brown bear loping along the shoreline, you won't want to miss a thing. Invest in a quality pair of binoculars that are powerful enough to focus on a moving animal. Adjustable cups will keep your eyes the correct distance from the lenses, especially if you wear glasses.

This may sound like overkill ... until it starts misting on an excursion. Layering with a hooded jacket and pants made of windbreaker-type material means the difference between staying dry or spending the day with wet clothes sticking to your body.

Alaska's climate can vary by the hour. When the temperature dips, add a fleece jacket over a t-shirt or under a waterproof jacket. A warm knit hat is key when your ship is docked next to a glacier, while nylon gloves work best by providing warmth without being so bulky that you can't operate your binoculars or camera. If you are sensitive to cold weather, silk long underwear can also save the day.

Planning on a walk on a glacier or a hike through the woods? Water-resistant or waterproof boots will give you grip and keep your feet dry way better than sneakers can. Invest in a good pair, and be sure to break them in before your cruise. No one wants to spend their vacation nursing blisters.

You'll want your hands free to take photos of wildlife and the pristine Alaskan scenery. Ditch the purse for an all-purpose backpack big enough to stash your extra layers, binoculars, and camera (plus a snack).

Don't think because you are heading north you won't have to worry about UVA and UVB protection. The sun shines intensely in this northern climate, and it's very easy to get sunburned quickly, especially if you are spending the day on the water while boating or fishing.

Mosquitos aren't as much of a pest in southeast Alaska (where most cruises go) as in the state's interior, but if the weather is rainy you might have to start swatting. Throw some bug repellent into your bag just in case. (We recommend the wipes to avoid sticky spills in your luggage and backpack.) Adding a post-cruise tour of Denali? Then this is a must.