Fort DeSoto is a Pinellas County Park just south of St. Pete Beach and due west of the Sunshine Skyway Bridge and is easily reached off of I-275.  The park is huge with miles of pristine beach.  For the birder, a popular destination is the last parking lot to the north end of the park called North Beach.  It is a short walk north along the beach to a lagoon with wading birds and of course the shoreline is full of shorebirds.  It is in the north/south migratory flyway so certain times of the year feature a plethora of species.  Check eBird for recent sitings.  Also popular is East Beach and the East Beach turnaround which faces the bridge, a great sunrise destination.  Note that it is around four miles from North Beach to the East Beach turnaround.  While I focused on shorebirds on my visit, it is home to many other species such as tanagers, warblers and even parakeets.  Keep an eye out especially around the pier and fort.  Restrooms are available