The atmosphere on expedition ships is casual, so formal clothing is generally not needed. Comfortable attire that allows for easy movement and active days ashore is helpful.
Most importantly, you'll want to pack gear that is appropriate considering the climate in the region you'll be visiting. For cruises to colder regions such as Antarctica and the Arctic, for example, there may be special packing considerations. Here, layering is best, especially with sweatshirts or silk or wool turtlenecks. You'll need waterproof polypropylene or fleece gloves, a hat and warm, waterproof pants, which can be layered over casual pants such as jeans, corduroys, sweatpants or thermal underwear.
In these colder regions, you might also be required to carry a waterproof parka (some cruise lines will provide this) and knee-high rubber boots for excursions on land. A pair of comfortable, rubber-soled walking shoes is a must for walking on deck.
Below are some additional considerations for packing. Your Vacations To Go travel counselor will also be able to provide you with a more detailed packing list for any itinerary you choose.