Seeing dolphins is almost guaranteed on Captiva and King Fisher cruises.

The passengers lining up to board the Lady Chadwick probably don't recognize the sharp class distinction among them. But it's there, all right, because about half of these Captiva Cruises voyagers will visit Cabbage Key, in laid-back, Jimmy Buffett territory, while the other half will spend an hour or two in the lap of luxury, on privately owned Useppa Island. The two tiny islands, only minutes from one another, are on the Intracoastal Waterway on Florida's Gulf Coast, just north of Fort Myers.

Between them, they are a microcosm of Floridian history and culture. Cabbage Key seems transplanted from the mellow Florida Keys, while Useppa could be an off-shore enclave more suited to upscale Boca Raton or Palm Beach. But each has their own unique attraction for day-tripping tourists.

Cabbage Key draws several visiting cruise boats each day, as well as individual boaters. Boats, by the way, are the only way to reach either Cabbage Key or Useppa.

The main Cabbage Key attraction is a restaurant and inn built about 12 metres above sea level, on the foundations of a Calusa Indian shell mound, and, just as importantly, on two more modern bits of history ... or legend.

One of those stories relates to the quintessential Florida singer/songwriter, Jimmy Buffett, whose anthemic Cheeseburger In Paradise may --or may not -- have been written about Cabbage Key. Buffett apparently won't pass definitive comment, so the legend lives on, and hundreds of commemorative cheeseburgers are consumed daily at the busy restaurant.

You can dine indoors or on the patio, where you will likely be visited by resident lizards and wandering turtles. If you opt for the patio, though, you should also wander inside, to discover the fruits of legend number two. The story goes that, in 1941, a fisherman, down to his last buck and on his way out for a day of tarpon fishing, signed a dollar bill and taped it to the wall of the bar, to ensure he had enough for a beer -- or maybe a cheeseburger -- upon his return.

The eccentric practice caught on, and today, the restaurant is papered with more than $30,000 -- some say, $60,000 -- in autographed dollar bills, including some signed by celebrities. One, of course, autographed by Buffett himself.

The notable bills are permanent, but the other money -- which has been known to blow off the walls and ceilings in a sharp breeze -- is recycled to charities including marine research.

Such is the fad, though, that the spaces are never empty for long.

Captiva Cruises has exclusive rights to dock on Useppa Island.

The inn has only six guest rooms (there also are a few cottages), so most visitors spend mere hours on the island. Visitors can also wander the "nature trails" --a short wander, if truth be told -- and climb the observation tower to, well, observe. But the real attraction is fast food with panache, a cold beer or two, and a certain sense of heritage.

The modern history of Cabbage Key dates back to 1938, when American playwright Mary Roberts Rinehart and her family built the joint. More ancient history -- the story of the Calusa Indians -- goes back to more than 1,000 years BC.

The local aboriginal story is well documented at a clever museum at the other Captiva Cruise destination, Useppa.

Useppa was apparently one of the first identified locales of human habitation in North America. The museum suggests that humans were living here 10,000 years ago. It, too, features shell mounds left by the reportedly now-extinct Calusa Indians. There is debate about that, though, with many arguing there are Calusa descendants among Florida native peoples.

Today, the lifestyle on Useppa is considerably more comfortable than it was thousands of years ago, which was turned into an exclusive luxury resort by Barron Collier at the same time Rinehart bought Cabbage Key. Useppa is still owned by a private club.

Once an exclusive luxury resort, the island is still privately owned.

Captiva is the only cruise line with rights to land here. Visitors can tour the museum and dine in the elegant country club-style Collier Inn -- but only in the area designated for tourists. The patio is sadly off limits.

The stop also includes the chance to rubber-neck, wandering around manicured pink paths and noting the authentic "old Florida" architecture and some rather spectacular private gardens.

The museum also provides a look into an unlikely period in Useppa's history -- the island was used as the training centre for the abortive Bay of Pigs invasion of Cuba. That story is well told in the excellent exhibit.

Captiva Cruises, based on Captiva Island (the northern half of Sanibel Island), is the only cruise line to visit Useppa. Other boating businesses, including King Fisher Fleet of Punta Gorda, make the trip to Cabbage Key.

I would take the King Fisher expedition to grab a cheeseburger, and en route see the natural beauty of Charlotte Harbour, arriving from the north; and later take Captiva Cruises from the south to Useppa. On both voyages, passengers are virtually guaranteed sightings of frolicking dolphins.

You'll also learn a lot about the history and the ecology of the area -- a part of Florida in which the natural environment is surprisingly well-preserved.

MORE INFORMATION

Cruises are $21.95 (King Fisher Fleet, about a seven hour trip), and $30 (Captiva Cruises, a five-hour excursion). Visit the cruise lines at kingfisherfleet.com and captivacruises.com. For travel info, see visitflorida.com.