Cayo Costa and Cabbage Key

Cayo Costa is the barrier island that most visitors imagine when they think of undeveloped Florida: miles of empty Gulf beach, wind-bent pines and not a single road. Reaching it requires a boat, which is part of why the shelling is so good, because few people walk the sand and the tide line is full of whelks, conchs and scallops. This guided excursion pairs a morning on Cayo Costa State Park's beach with lunch at Cabbage Key, a small island in Pine Island Sound whose inn and restaurant are famous for walls and ceilings papered with signed dollar bills. The trip crosses shallow, wildlife-rich water, so dolphins and birds often appear along the way, and the whole outing feels like a step back into a quieter, older Florida that has little in common with the busy beach towns.

The boat journey is a highlight in itself. Pine Island Sound is a shallow, mangrove-fringed estuary, and a good captain knows where dolphins feed, where ospreys nest and which channels are safe at which tide. On Cayo Costa you can walk the beach for shells, swim, picnic or explore the island's trails; the park also has primitive cabins and campsites for people who wish to stay longer. Facilities are basic by design, so expect few services and plenty of space.

Cabbage Key is the other half of the day. The island was once the home of author Mary Roberts Rinehart's family, and the inn that occupies the property is known for a long-running tradition of guests signing dollar bills and pinning them to the walls. It is also said to have helped inspire a song about a cheeseburger in paradise, and the restaurant remains a popular lunch stop for boaters. Allow time to climb the small water tower for a view over the sound, walk the grounds and look at the bills.

This is a full-day commitment and one of the priciest options in the region, because it uses a private or small-group vessel, so it works best as a special day. Bring sunscreen, a hat, water, a bag for shells, towels and cash for lunch, and wear shoes that can get wet.

Remember that on state park land you must leave live shells in place and follow park rules. Confirm departure point, inclusions, group size and the weather policy when you book, since conditions in the sound affect timing. Done well, it is the most atmospheric single day you can spend in the area.

Timing and tide shape the day, so listen to your captain when planning how long to stay on the beach. The best shelling often comes at low tide and after a blow, and the walk from the landing to the Gulf beach takes a little time. Keep an eye on the sun, which is strong on an exposed beach with little shade, and drink water before you feel thirsty.

If you are interested in staying longer, the state park's cabins and campsites must be reserved well ahead, and visitors who camp are rewarded with star-filled skies and empty sand at dawn. Bring a small cooler for drinks if the operator allows it, and pack a light rain jacket, because afternoon showers can blow through the sound with little warning.