The surfing here is not great by Bali standards but there are reasonable breaks about 1km offshore during the northwest wind season (about October to March). In that period you will have no problem locating the breaks - just follow the locals.
The more active can try one or more of the many water sports on offer at Sanur Beach. Try kite surfing, windsurfing, wakeboarding, surfing or paragliding. For those less active, hire a banana boat and hit the calm waters