Ilha Grande is an enormous bay packed with islands, the east of Rio de Janeiro. The main village is Vila do Abraao and there are about 100 deserted beaches around the island, some of which can get very busy in holiday periods especially the night life. Once a pirate lair and landing stage for slaves, it was a leper colony in the 19th century and a high security prison until 1994. Most of the island is now a state park including the Reserva Biologica da Praia do Sul where you can see exotic birds and also surf the day away.
The Ilha Grande is exactly that a Big Island.
It also has big thins to do like sail the bay, you haven't been sailing until
you sail off the coast of the Big Island.
There is also forest trekking,
sea kayaking, surfing, and even snorkeling. The opportunities are endless.
So if you want to have big fun go to the Ilha Grande or Big Island.