The island of Cayo Costa off the coast of Lee County, north of Captiva, is only reachable by boat, and most of it is a state park offering primitive camping. But, the still-unspoiled island has a rich history that we’re exploring in advance of the new independent documentary Mullet & Mangroves that airs starting Thursday, July 12 on WGCU TV . It tells the island’s story through historical research and interviews with the few remaining pioneers who grew up on Cayo Costa.