Once in Uruguay, I left Chuy by bus to reach La Coronilla from where I walked the 20km until Punta del Diablo with all my stuff throw the Santa Teresa National Park. Actually,
I didn't walked straight ahead, so it was much more than 20km. The park have a camping. It may have been better using it and doing the way in two days.
In that park, we can find the Fortaleza de Santa Teresa, a star-shaped fortress, and a few beaches.