Pony Penning Day is an annual event held on Chincoteague Island, Virginia, where wild ponies are rounded up and swim across the Assateague Channel. This tradition dates back to the late 19th century and is part of the local culture, celebrating the unique Chincoteague Pony breed. During the event, spectators gather to watch the ponies swim to the island, where they are then herded into pens. Afterward, some ponies are auctioned off to raise funds for the local fire department and to support the care of the remaining wild ponies on Assateague Island.