Mustang Island is one of several barrier island's along the Texas Gulf Coast. It is about 18 miles long, and usually no more than two miles wide. At the north end of the island is the town of Port Aransas. Here, Mustang Island is separated from St Joseph's Island by Aransas Pass. At the southern end, Mustang Island is separated from Padre Island by Packery Channel. The Island gets its name from the wild horses that once roamed here.

The Island is also home to Mustang Island State Park. All of the beach on Mustang Island is accessible by car. However, there are two areas were driving along the beach is blocked. At the southern end of Mustang Island State Park, the beach is blocked by a series of posts. On the northern side of the park, the beach is blocked by the remnants of Fish Pass. Parking stickers are required for most of the beach on Mustang Island. However, there is free parking between Access Rd 2 and Fish Pass and between the Horace Caldwell Pier and the Port Aransas Jetties.