Alex D.
Yelp
Well, this lagoon is basically the epicenter of the "Zona Sul" of Rio - the trendiest center of the three historic neighborhoods of the area - Leblon, Ipanema, and Copacabana, which are basically triangulated around it.
It's a great place to exercise and people watch, and the real estate around here has skyrocketed as Rio has been further developed. I still miss seeing the rickety old amusement park that I used to beg my parents to bring me when I was a kid - Tivoli Park, but I am sure that my own memories of the park are much better than the park itself was.
Walking around the Lagoa on the trails is always fun, since there are so many beautiful sights to see - both geographic and human. It's a great place to people watch, since there are folks from all walks of life parading around. If you are planning a stay in one of Rio's "apart-hotels," try and get one that is convenient to this area, close to Ipanema beach, because of the many shops, restaurants, and other fun things to do here. If you get the opportunity to swim in the lagoon, don't. I'm not sure you would come out alive - there's nastiness in those waters. Great sights all around, though.