 Legend has it that the feral ponies on Assateague are descendants of survivors of a Spanish galleon that sank on its way to Spain during a storm in 1750 off the east coast, but the likelihood is that they are actually descended from domesticated stock, brought to the island by Eastern Shore farmers in the 17th century to avoid fencing requirements and taxation.In the Pony Penning, which has been held annually since 1925, horses swim across the shallow water between the islands.At "slack tide" on the Wednesday before the last Thursday of every July, Chincoteague's "Saltwater Cowboys" herd the wild Chincoteague ponies from Assateague Island, across the Assateague Channel, to neighboring Chincoteague Island.