The principal activity here is wildlife watching from a vehicle or on foot. Guided tours can be arranged in Ituzaingó. You can contract a tour with transportation or organize a guide to jump into your own vehicle. It's well worth taking a professional guide as they know where to find the wildlife and spot animals a casual observer may miss.
Overnight stays are not permitted within the national park boundaries here. The closest accommodations to the park are in Ituzaingó on the banks of the Río Paraná where there are several good budget hotels and some more luxurious options.
There is a lovely large grassy picnic area by the visitor's center equipped with barbecues but you'll need to bring everything from Ituzaingó as there are no shops nearby.