Just remembered one additional heads up about Assateague. The horses may be wild (sort of) but they are used to being around people and like people food. Don't leave anything that looks like or smells like food outside your vehicle when you are away. And yes, they do know how to open coolers. The woman in the picture was trying to chase them off, with little success until others in her party came to help.
P.S. Just because the horses seem tame doesn't mean that they are, as the rangers will advise when you enter the park.
