Approximately 150 Chincoteague ponies and 50 to 60 foals swim from Assateague to Chincoteague during slack tide, when water currents are weakest. The Saltwater Cowboys lead the ponies into Assateague Channel for the quarter mile swim that lasts from seven to nine minutes. Guide boats insure that the ponies swim across the channel at its safest point. Pregnant mares, aging ponies, and mothers with foals under three months of age, are transported to Chincoteague by trailer.