This page is to inform people about how many types of Cadillac Boats were built for a teaching, commentary, and research purposes only
This is a 1957 Cadillac boats ad by Cadillac Marine & Boat Company by Brian Fogarty  below 
                                                   This is a 1955 Cadillac boats ad by Cadillac Marine and Boat company by Brian Fogarty
This is a 1957 Cadillac boats ad - Seville, Bar Harbor, Riviera, Coronado by Cadillac Marine and Boat Company by Brian Fogarty
This forum is talking about the Cadillac boats https://forum.tinboats.net/viewtopic.php?t=34294 by TinBoats - The original aluminum boat site!  This website is cool site. Thank you for sharing
This is a Cadillac "Custom " Aluminum Model or a Wagemaker " Custom " Aluminum Model below Thank You Brian Fogarty 
The Evinrude LARK SPORTSTER - In 1956, Evinrude asked Brooks Stevens to design a boat to complement the styling of the new Evinrude 35hp Lark outboard he had designed. What Stevens came up with was possibly the wildest boat anyone had ever seen up to that day - the Lark boat & motor combo. With massive tail fins, a striking paint scheme, only two seats, and a double-bubble windscreen, the Lark Sportster with its matching Lark outboard was a true attention getter.
The Cadillac Boat Company was commissioned to build the wood, fiberglass, and aluminum curiosity for Chicago and New York International Boat Shows. (It’s not clear when the switch happened but in some boat show photos the boat was called the Cadillac Sea Lark.) It is believed that Cadillac Boats built one for each show, then never built another one again. Both were apparently lost to time but there is, however, a replica built by boat builder/restorer Gary MacNorious that makes the boat show circuit. story by Jack Aylsworth see below 
This is a good story about the "THE HOLY GRAIL OF 50S BOATING". Provided by Brooke King and crediting by PropTalk see below   https://www.proptalk.com/holy-grail-50s-boatifbclid=IwAR0RYuGir7OzVXFizWeuiVypnqlvhjz5_11546aYeAQQ2EVOiM-M94frC8o
This is a 1956 Cadillac boat ad by Cadillac Marine and Boat Co. by Brian Fogarty