Just days before Earth Day, visitors to Hilton Head Island, South Carolina, began lining up to experience the tourist destination’s newest attraction: ¬†Zipline Hilton Head. As the Island Packet reported on opening day, the ride, which sends riders suspended from a pulley down gradually sloping wires tethered to a series of treetop towers, mixes family fun with a dose of ecotourism (zip liners can learn about the delicate balance of nature from the company’s hired ecologist/guide) on an island whose early developer pioneered an aesthetic blend of subdued architecture with Lowcountry nature that has until now provided mainly a sylvan backdrop for decidedly calmer forms of recreation. On the face of it, zip lines seem most closely tied to other, more “extreme” forms of…