All the big cruise lines offer Alaska Cruises often using their slightly older smaller ships as these tend to be able to take their clients closer to the all important Alaskan glaziers.
Cruises in and around Alaska tend to start from Vancouver, Canada or the western coast of the USA from either Seattle or San Francisco. Many people take the opportunity to visit Canada either pre or post cruise to experience the Rock Mountaineer Railway which winds it way through the Rockies, offering an unforgettable extension to the cruise.
Alaska Cruises probably has more repeat cruises than any other type of cruise.