A perfect summer of surfing, snorkeling, and skateboarding turns into a season of daring adventures and exploration for three young friends after they rescue a local swimmer from drowning. Buzz, Oz, and Jimbo, dubbed "Grommets" by the older wave riders begin their action-packed summer when they find a treasure chest on the ocean floor with a map that leads them into the dangerous tides and treacherous passageways of Turtle Cave. What secrets are hidden behind the massive wooden door? As the boys rush from riding waves to scrambling through damp cave tunnels, they test their limits against the ocean and push the boundaries set by their parents and society learning to be true to the Grommet's code of integrity.