If you plan to travel on the Alaska Marine Highway System (the correct name if I recall correctly) keep in mind it is not a cruise ship. Rooms are hard to get and must be reserved very early. If you don't have a room you get to sleep on the deck lounge chairs or inside in one of the sitting rooms. Some people pitch a tent on the deck of the ferry, a windy, cold soggy experience if the weather is poor. The weather is often poor on the way to Alaska.

Also, keep in mind it is a working ferry, used to support commerce in and for the state of Alaska. They are not there to provide a cruise experience. However, if you can live with those limitations, you will find the trip very enjoyable. Lots of great people, interesting conversations, and, weather permitting, beautiful scenery. I strongly suggest bringing a sack of drinks and snax so you don't have to live with the awful ferry food.

The ferry being smaller than the big cruise ships can get closer to the islands and travel through inlets that the big ships can't safely navigate.

Best wishes, Paul Greater Seattle