Rio de Janeiro, Niteroi Ferry
One of the recommended excursions in Rio is taking the public ferry that crosses Rio's Bay. From the ferry you will have a spectacular view of the Financial District.
If you want to take the ferry, you have to take a taxi to Praça XV (or Square 15). Go to the Bilheteria (ticket office), and buy a return ticket to Niteroi. The ferry ride lasts around half an hour. Boats leave every half an hour.