Pirates. Castaways. Ship wrecks. Gold Doubloons. The allure of Matagorda Island is legendary, and you may hear tales of locals finding antiquities encrusted in the island’s slate gray sands. The discovery of French explorer Robert de La Salle’s 17th-century ship, La Belle, reawakened the furor, and treasure hunters can now be spotted scrutinizing every inch of the 30-mile island, which occupies a strategic section of the gulf near the mouth of the Colorado River. A destination for Robinson Crusoe types unafraid to rough it, Matagorda attracts campers and backpackers aplenty, too. Take your kids and build driftwood huts, search for shells, or have a picnic. If you stay the night, consider a dip in the sea, which sometimes is illuminated by phosphorescent algae.