The 60 southern miles of 'North' Padre Island that lie beyond Corpus Christi city limits are protected within the Padre Island National Seashore. Endangered Kemp's ridley sea turtles nest in the park and are closely safeguarded. Visit in late summer, and you might be able to take part in a turtle release.
The constant wind not only creates and moves dunes, it also attracts kite- and windsurfers to the inland-facing Bird Island Basin area. There you can rent kayaks, windsurfing gear and stand-up paddleboards from Worldwinds.
It takes 4WD to explore the full extent of the park, but hike even a short way from the visitor center and you'll escape the crowds. Camping is available at the semideveloped Malaquite ($14) and Bird Island Basin ($8) campgrounds, or go primitive – beach camping elsewhere is free, with a permit.