Lodges can organize most activities; they are usually included in the accommodations price. Otherwise, the best place to organize boat trips and other excursions is the campsite (from where most trips leave). Note that few guides speak English; if you want an English-speaking guide, it’s best to go through one of the lodges.
There are several short hiking trails leaving from the visitor center, the longest of which is about 2km. During the day you are free to hike at your leisure although its worth taking a guide (AR$150 to AR$200 per visitor) in order to learn about the ecosystem and to point out wildlife you may otherwise miss. For nocturnal exploration, guides are obligatory.
You can rent kayaks and canoes (per hour AR$100) at the municipal campground for exploring the laguna at your own pace.
Horseback rides (AR$280) are also offered around town, although these are more for the ride’s sake than for wildlife spotting.