Since many of the beaches in Ilhabela are only accessible by boat I highly recommend doing one of the boat tours. There are all different types of boats to choose from so you can go with whatever you are most comfortable with and separate tours for the north and south sides of the island. I prefer speed boats so we went on a speed boat tour with about 15 other people to the North side of the island which cost R$140 per person (on average this was the cost for almost every tour). At the end of your tour you take a jeep through the rain forrest back to where the tour started.
For the North side of the island tour you will stop at 3-4 different beaches on your way to Baia de Castelhanos Beach. Our first stop was Praia Fome (above). The beach is known in the region for an old house (300 years old) that was inhabited by slaves at the time of colonial Brazil.
We stopped at 2 other smaller beaches before ending at Baia de Castelhanos Beach. From the water you can see Cachoeira Gato which is 80 meters high(if you want to hike it plan ahead!). The beach is beautiful, 5-6k of white sand, and there are a few restaurants that line the beach so it was perfect for lunch (great fresh fish) and it is one of the few surfing beaches in Ilhabela. Make sure you wear a LOT of bug spray!!! The beach closes at 6pm which means the jeeps leave the area at 4pm. The Jeep ride back was a lot of fun, driving through the rain forrest is beautiful and you see a few waterfalls like Cachoeira Branca below!
Check out some more pics of the beaches we visited on our boat tour below, have a great trip!