Captiva Island is very small so regardless of where you stay you'll never be far from the water.  Not surprisingly, the majority of things to do are water oriented.  Yolo Water Sports on Andy Rosse Lane offers parasailing and wave runners, which must be used with great care due to the presense on dolphins and manatees all around the island.  Bikes and skates as well as body boards can be rented, but Captiva is not a good choice for any of these activities.  The bike paths on Sanibel are safe and extensive.  There are none currently on Captiva.  You'll share the narrow lanes with trucks and cars and have nowhere to go and plantings come right to the road's edge in most places.  Do your biking and skating on Sanibel.  Sailboards work well bayside, but the best location most days is right off the little man made islands that anchor the causeway.  For whatever reason, the bay usually has better breezes.  Surf is usually very low, but on breezy days and body board might be useful and fun.  Captiva Kayak rents canoes and kayaks.  The bay is great for kayaking and the favorite spot to to go down to Buck Key, a protect island just off the bayside of Captive on the Sanibel end.  Captiva Kayak offers naturalist  guided tours as well - a good way to learn more about this history of the area and the remarkable sealife life that bays and estuaries nurture. Go in the morning during the summer months. The heat can be overwhelming.  Be sure to wear high SPF sunscreen.

Captiva Cruises offer a number of different trips on its large, comfortable boats.  In the morning you can go to Cayo Costa, Cabbage Key, Useppa Island, or Boca Grande.  They also offer a Dolphin Cruise and a Sunset Cruise with island favorite Danny Morgan doing the live entertainment.  Schedules change with the season and weather.

Private charters for fishing and shelling sail from Jensen's Marina, McCarthy's and Tween Water's.  Charter Captain's supplies bait and guides you to active spots.  Flats fishermen love the sandy areas around the mangrove islands.  Sea trout, tarpon and snook are among most sought after game fish.  You can also surf cast off the beaches, just be aware of swimmers.

South Seas Island Resort has a 9 hole golf course and it's own marina, but these and their other facilities are for the exclusive use of the resorts guests.

For more things to do, see the various activities available on Sanibel, Captiva's southern neighbor.