Jack Stark
There is little information on Jack Stark on the internet, but it has been confirmed by his granddaughter, Jenn Stark that he wrote several children's Eas-y books. Stark also worked for the Miami Herald and early on did public relations work for the Indies House. A book entitled The Sponge Pirates and Other Stories authored by a Jack Stark in the early 1950s has a chapter entitled "The Sunken Treasure of Plantation Key". The chapter makes mention and describes places in the middle keys. Some place names used will still be recognized while others have changed with time: Valhalla Beach Club, Valhala Beach Motel, Bonefish Bay, Pelican Motel, Greyhound Key, and Art McKee's Treasure Fort in Plantation.
The first edition published (1956) by Hopkins Publications of Miami had 78 pages.
In 1956 a limited second edition of 86 pages was also published and sold at Art McKee's Sunken Treasure Fortress in the Florida Keys. The second edition added a page entitled, "Treasure Diver", and included a full page photo of Art Mckee (see reference to Chapter 3 below).
A paperback edition was published by Hurricane House in 1962. Interestingly Hurricance House Publishing out of Coconut Grove was started by Marjory Stoneman Douglas. The earliest publication printed by Hurricane House appears to have been SPONGE PIRATES AND OTHER FLORIDA KEY STORIES (1962).
Douglas published a number of books with titles such as Bromeliads In Cultivation by Catherine and Robert Wilson, Indian River Florida’s Treasure Coast by Walter R. Hellier, Some Kentuckians and Other People by Mary Willis Shuey, Poisonous plants on Guam by P. Souder, "Eve's Daughter" by Hannah Kahn, Plants Poisonous to People in Florida and other Warm Areas by J. F. Morton, Tampa Town, 1824-1886, The Cracker Village With A Latin Accent by Anthony P. Pizzo. Douglas also reprinted her Everglades River of Grass
Another hardback edition of the Sponge Pirates was published by E.A. Seemann Publishing, Miami in 1972.
An image of the cover appears below:

Of particular interest to residents from Duck Key is Stark's description of the island,
"As they drove past Duck Key, they marveled at the rock gates which rose before them, leading to the small wooden bridge crossing to an island shaped like a duck's head. tall palms rose along the causeway, and farther inland they could see the pretty West Indies-style buildings."
Further along in Chapter Three several children experience a diving adventure with McKee. McKee started a public museum exhibiting sunken treasure on Plantation Key at Treasure Harbor. Several years later McKee opened a larger "Sunken Treasure Museum" on the Overseas Highway at Plantation Key. The museum was built to look like a fortress, with ramparts and cannons. Later the museum changed ownership, was expanded and partitioned into stores and presently it functions as a Montessori school.

Sunken Treasure Museum
Image above is from Florida State archives and is part of the Florida Memory Project photo collection.
http://www.floridamemory.com/PhotographicCollection/Collection_page.cfm?PR_ID=30
http://ibistro.dos.state.fl.us/uhtbin/cgisirsi.exe/QPT7lTWCkS/STA-FLA/20090003/9
The other Eas-y Book written byJack Stark published by E. A. Seemann Publishing was entitled Loggerhead. The book was about a boy turtle wrestler from Key West who catches a giant loggerhead turtle to star in the wrestling attraction at the Turtle Pens.
Through granddaughter Jenn Stark we were able contact other family members of Jack Stark and hope we can obtain additional information about his work, interests and involvement with Duck Key and the Florida Keys.