The best swimming in the area is at Mustang Island [1] State Park, but visitors can still access portions of the wide and welcoming beach amongst the condos and private property just off the island’s main road (Hwy. 361).
Visitors can also swim and camp at the northern tip of the island just outside Port A at Magee Beach Park (321 North on the Beach, 361/749-6117, nuecesbeachparks.com). This 167-acre park isn’t quite as breathtaking as other portions of Mustang Island or San Jose Island [2], but it’s a good spot to dip your toes in the water and soak up the salty sea air. A new park office offers limited visitor information and the beach bathhouse contains publicly accessible showers.
Links:
[1] http://www.moon.com/destinations/texas/the-gulf-coast/corpus-christi/recreation/beaches
[2] http://www.moon.com/destinations/texas/the-gulf-coast/corpus-christi/port-aransas/san-jose-island