As of 2014, there were 10 National Seashores.
The 2 National Seashores visited by Gram and Pops are listed in black.
You can see pictures of their trips by going back and clicking
on the List of Visited Parks link above and then selecting
National Seashores Visited by Gram and Pops.

Name
      Location
Assateague Island National Seashore       Maryland, Virginia
Canaveral National Seashore       Florida
Cape Cod National Seashore       Massachusetts
Cape Hatteras National Seashore       North Carolina
Cape Lookout National Seashore       North Carolina
         
Cumberland Island National Seashore       Georgia
Fire Island National Seashore       New York
Gulf Islands National Seashore       Florida, Mississippi
Padre Island National Seashore       Texas
Point Reyes National Seashore       California