Here is a listing of cruise lines and their vessels. One caveat: Many cruise companies prefer to sell through travel agents. It's often best to book through an agent who specializes in cruises.

American Canadian Caribbean Line
(800) 556-7450
http://www.accl-smallships.com

Grande Caribe, Grande Mariner, Niagara Prince.
American Cruise Lines
(800) 814-6880
http://www.americancruiselines.com

American Eagle, American Glory.
American Safari Cruises
(888) 862-8881
http://www.amsafari.com

Safari Escape, Safari Quest, Safari Spirit.
American West Steamboat Co.
(800) 434-1232
http://www.columbiarivercruise.com

Empress of the North, Queen of the West.
Carnival Cruise Lines
(800) 327-9501