Water sports and tourism are king throughout the Hawaiian Islands. Surfing, paddling and kite boarding are very popular water sports with plenty of rental equipment available.
Haleakala National Park
is also a big draw and worth the drive to look inside the crater rim at 10,000+ feet.
If you just want to experience the beauty and laid back lifestyle of Maui then a drive to Hana
might just do the trick. It's a long, winding and scenic road.