kite surfing
This is one of the best spots in the world for kite surfing. Several places rent equipment and give classes.Since 5 years [Extreme Control Kiteboarding (http://www.extremecontrol.net)] offers Personal Training in Cumbuco
jangada
A jangada traditional fishing raft with sail will take you a kilometer or so into the sea to give you a different view of the beach. Nice photos from out there. R$ 10 or less per person.
Horseback riding
Along the beach.
buggy with a driver
A buggy with a driver can be rented for a day for about R$ 150, -fits 3-4 passengers. It will take you to 2-3 different fresh water lakes for swimming, and also for a ride up and down some dunes.
rent a buggy
You can also rent a buggy and drive it yourself, but you will not have access to the dunes. It is nominally prohibited to drive on the beach, but this is not enforced.
Rent an ATV
To make sure that you disturb other people's beach experience.