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.