For Mick Baron, the giant kelp forests of Tasmania were a playground, a school and a church. The former marine biologist runs a scuba-diving center on the Australian island’s east coast, and rhapsodizes about the wonders of the seaweed’s dense habitats. “Diving in kelp is one of the most amazing underwater experiences you can have,” the 65-year-old says, likening it to flying through the canopy of a terrestrial rain forest.