One of the best ways to experience a national park is to take part in an interpretation program of some sort, one that delves a bit deeper into the landscape or history of the park.

At Death Valley National Park, for instance, the guided tours of Scotty's Castle in Grapevine Canyon are indispensible for first-time park visitors. Led by knowledgable guides in early 20th century garb and who respond to you as if it were indeed early in the 20th century, these tours of the opulent "castle" open your eyes to a desert rat and a Chicago tycoon who found friendship in the desert.

Ranger-led tours of the cliff dwellings at Mesa Verde National Park are the best way, and in some cases the only way, to explore the incredible chapter of history told at the park.

Another addition to great ranger-led tours comes early next month when Biscayne National Park unveils its Maritime Heritage Trail guided snorkel tours. These three-hour tours start Saturday, May 7, and will be offered twice daily every Saturday, with tours departing at 10 a.m. and 1:30 p.m.

Along the maritime trail are six shipwrecks that span nearly a century in time and include a range of sizes and vessel types, such as schooners and steamers. To help promote the trail, and to educate those who follow it, Biscayne officials have mapped it, provided mooring buoys for those who want to explore it on their own, and produced waterproof site cards for each of the wrecks.

While most of the wrecks are best explored by scuba divers, park officials say the Mandalay, a 112-foot-long steel-hulled schooner that sank on Long Reef on New Year's Day, 1966, is within reach of snorkelers. The schooner, which was built in 1928, was en route from the Bahamas to Miami when it ran aground. At the time it was known as the “Red Carpet Ship of the Windjammer Fleet” and was outfitted with a teak and mahogany deck, according to the park.

Although this tour is perhaps a bit spendy, at $45 per person, that cost covers a boat ride out to the trail, all the necessary gear (mask, fins, snorkel, snorkely vest) and, of course, the ranger.

During the trips a ranger will provide an overview of the park and the submerged cultural resources before leading an exploration of a selected shipwreck. Park officials say the tour is suitable for the novice and experienced snorkeler alike, but all participants must be able to swim.

These tours are being arranged by the park's concessioner, and you'll need to make reservations if this sounds like fun to you. Reservations can be made by calling 305-230-1100, or by visiting www.biscayneunderwater.com . All of the trips set out from the park's Dante Fascell Visitor Center, 9 miles east of Homestead, Florida.