If you aren't tired of the water (considering you cruise half your life), the Reserva Ecológica Costanera Sur is just at your doorstep. Cover yourself with mosquito repellent though, March is a good time for them.
You could also try the trains, they are the cheapest mode of transport and they bring you quite far. The north line goes up to Campana, the south line goes to La Plata, capital of the province, and various others that run towards the west. On trains language is not a huge problem, station names and route are fixed and mapped nicely, you can't really get lost if you use stations as landmarks.