I’ve had the pleasure of visiting Rio de Janeiro a few times recently and it’s always a fun experience . Rio is probably the most beautiful city in the world along with Cape Town in South Africa where I grew up. I would say they are about equal in their beauty while both having their own unique flavor , but I am always reminded of the Cape Town life style when I’m in Rio .
The water at Ipanema beach can be surprisingly clear on a good day and there is some good snorkeling around the rocks on the far left of the beach. I believe you can go scuba diving around the Cagarras Islands in front of Ipanema by boat , although I’ve never had the chance to do it , but they do look interesting to explore.
In my experience , Rio is pretty safe to visit as a tourist as long as you use basic common sense. As a tourist the majority of your time will be spent in the “Zona sul” , or “South Zone” . This is where most of the famous places in Rio are found ,like Copacabana beach , Ipanema , the Corcovado mountain with Christ the Redeemer and Sugarloaf Mountain known as “Pão de Açúcar ” in Portuguese . This region of the city is safe and well policed with a good bus system . I have also stayed in the North Zone near Barra da Tijuca.This area is also pretty decent , with some very nice beaches , but the area has a more modern Americanized feel to it with lots of large malls , condominium blocks and fast food joints, it’s also far from the attractions of the South zone and you can spend over an hour on busses to get from the far side of Tijuca to Copacabana. Get yourself a public bus card and on each trip you can travel for over an hour , regardless of how many times you have to change busses , pretty good value to travel a long distance in Rio. I often hopped on a 9pm bus to traverse Rio from the South to the North , changing buses at terminals and waiting at bus stops and did not have any problems.