A = Assateague Island National Seashore. It is located off the coast of Virginia, near Chincoteague Island. Wild ponies live there. Once a year the local fire department rounds them up and swims them across to Chincoteague. It is a big event/weekend. The ponies receive vaccinations and other medical care. Some ponies are auctioned to pay expenses.
The children’s book, Stormy of Chincoteague, is about these ponies. There are several books in the series.