Drift models based on wind and ocean currents have shown that coconuts could not have drifted across the Pacific unaided. If they were naturally distributed and had been in the Pacific for a thousand years or so, then we would expect the eastern shore of Australia, with its own islands sheltered by the Great Barrier Reef, to have been thick with coconut palms: the currents were directly into, and down along this coast. However, both James Cook and William Bligh (put adrift after the "Bounty" mutiny) found no sign of the nuts along this stretch when he needed water for his crew. Nor were there coconuts on the east side of the African coast until Vasco da Gama, nor in the Caribbean when first visited by Christopher Columbus. They were commonly carried by Spanish ships as a source of fresh water.