Marco Island is a 24 square mile barrier island in the Gulf of Mexico off Southwest Florida, and is the largest island within Ten Thousand Island area stretching southerly to Cape Sable. The story goes that during the time of Spanish exploration of Florida in the mid-1500s, the Spaniards stumbled upon a large island, which boasted two artisan springs, near present day Caxambas Pass. Initially, the Spaniards named the island La Isla de San Marco, which translates, the island of Saint Mark, named for Saint Mark, author of the second book of the New Testament in the Bible. Later, the island was named San Marco Island (Saint Mark's island) and ultimately, Marco Island.

The warlike Calusa Indians  are believed to be the first inhabitants of this remote island, dating back perhaps as early as 1450 B.C., with evidence of their existence first discovered in 1895 by  Captain Bill Collier, son of Marco's founder. W.T. Collier, who accidentally discovered a wooden carving while digging on his property in Key Marco, known today as Old Key Marco. The artifact was given the name "Key Marco Cat," and is now on display at the Smithsonian Institution in Washington. The Calusa Indians had built large mounds using millions of shells that served to guard against hurricanes, as well as for use as religious temples and burial sites. 

In 1896, son of W.T. Collier, William D. "Captain Bill" Collier opened a 20 room hotel, ushering in a new kind of civilization on Marco Island that moved beyond farming. Today it is known as the Olde Marco Inn and is registered as an historical landmark. In the early 1900s, clam digging became a major industry on Marco Island and throughout the Ten Thousand Islands region, with the Burnham Clam Cannery operating near Caxambas Pass from 1903 until 1929, and the Doxsee Clam Cannery which operated from 1911 to 1947. In 1922, Barron G. Collier (no relation to W.T. Collier) purchased most of Marco Island. 

Although there is very little wilderness left in Marco Island, it is a diverse habitat that features estuaries, mangroves, cypress swamps, forests and beaches, supporting many species of wildlife, including dolphins, manatees, black bears, sea turtles, shorebirds, bald eagles, osprey, burrowing owls, gopher tortoises as well as panthers. Bird watching, hiking, canoeing, kayaking, fishing and boating care some of the amazing activities that can be enjoyed on Marco Island.

All sizes are approximate.