What is "aquaduck"

AquaDuck is a water coaster (a water slide with similar turns, drops and g-forces to a roller coaster) that is located on the deck of two Disney cruise ships. It was first constructed on the Disney Dream in January 2011 and then later on the Disney Fantasy in February 2012. It was developed by Walt Disney Imagineers, and despite a few exceptions, is accessible to almost anyone. The AquaDuck is the first water coaster to exist on a cruise ship, and so far it is the only one of its kind.