Your itinerary ought to include a wander through University of Texas Marine Science Institute. It's a well-known local institute with a vibrant campus life.
You're spoiled for sightseeing choice when visiting Port Aransas. University of Texas Marine Science Institute is a great place to begin here, but there are loads of other worthwhile places to visit. Port Aransas Beach, Mustang Island Beach, and IB Magee Beach Park are near the modern university and and will cap off your day nicely.