Beneath the sprawling, gnarled branches of a kiawe tree in Hawaii's pristine Kealakekua Bay, an X lies carved into an otherwise unassuming rock face. But there's no buried treasure to be found here.

Captain Cook's enduring claim to fame is that he redrew the map of the world in three extraordinary voyages over the Pacific, north and south. The news that reached London in 1780 of his death on a ...