Growing up in Rome, I spent most of my summers at the Argentario peninsula off the coast of southern Tuscany. The day that school ended we piled into a car and drove the Autostrada Roma-Civitavecchia to the seaside town of Porto Santo Stefano, where my family has a home. Some of my most cherished memories are of day trips to the islands of the Argentario in our speedboat called Why Not? (we also had a small sailboat called That's Why—my mother's little joke). My cousins and I would anchor in a quiet cove, swim, snorkel, have a picnic, and lie like lizards in the sun until five in the afternoon, motoring back home at full speed for one last dip off the rocks under our house.
I now live in New York where I've raised a son and two very American daughters. We speak English at home, and they go to American schools and to summer camp. But every June we return to Italy to show them a small slice of the Mediterranean lifestyle I love. My mother, Suni (Agnelli), and my brother Lupo (Rattazzi) still own homes in Porto Ercole and Porto Santo Stefano, the main towns occupying each side of the peninsula. The terraces that frame each of the properties are what make them truly special. My mother's terrace sits right on the roof; Lupo's is part of an old Roman villa ruin, paved with ancient stones and mosaics. Both face west over the Mediterranean, and a favorite family ritual is to sit in the giant rattan beach chairs and watch the sun set over the sea.
My mother gave up Why Not? when she became mayor of Porto Santo Stefano 30 years ago, but I recently chartered a white 50-foot Baia speedboat named Sassy and a 50-foot Rizzardi called Blue Dream from Ferruccio Fronzoni, to take my daughters and other members of my extended family on the excursions of my youth. We toured all the stops on my old circuit: the islands of Giglio and Giannutri ten miles south of Porto Santo Stefano, the national park of the Uccellina, just north of the Argentario, another southern peninsula called Ansedonia, and just to the south, the very fashionable Capalbio. There, members of the country's elite rent homes in a superprivate compound protected by the World Wildlife Fund. The properties are simple and identical two-story white farmhouses that sit in a row, but they all face the stunning Lake Burano. I spent a whole day there photographing my friend Vera Arrivabene's house (available for rent in July and August, by the way) and artist Giovanni Sanjust's unusual estate, where he raises farm animals, peacocks, and wild boars and has erected sculptures made of hay bales. All serve as inspiration for his beautiful Tuscan landscapes, which manage to capture the beauty and simplicity of a very special place.
STAYING PUT IN STYLE It's an hour and a half drive from Rome to the Argentario peninsula—and to the spectacular Il Pellicano, the chic hillside Relais & Châteaux property that is really the only place to even consider staying put—for a night, a week, forever. Thanks to general manager Cinzia Fanciulli, everything—the lush gardens, the impeccable food, your chaise at poolside—is perfect (rates, $700-$1,775; 39-056/485-8111; www.pellicanohotel.com). There is also excellent train service to the area from Rome's Termini station (see www.trenitalia.it for schedules). Take it to Orbetello station and have a car or taxi pick you up.
IF YOU'RE RENTING A HOUSE on the Argentario peninsula, Rome-based Letizia Bucci Casari Pasolini is the broker both Mel Gibson and HBO turned to when filming in Italy (39-347/662-4298). Amanda Sposito, a Capalbio insider who rents one of the houses year-round, runs a much smaller operation, but she knows Capalbio particularly well (39-335/658-9205).
TO CHARTER A BOAT (which is really the best way to see these islands), contact Ferruccio Fronzoni at Corso's Charter. His 50-foot speedboats come with a two-man crew and a picnic, though he says all his Italian clients want is spaghetti ($2,500 a day; 39-056/483-0040).
BRING BACK one of Giovanni Sanjust's landscapes, available by commission (39-320/079-0657).