The very name conjures images of smuggler's coves and illicit peddling of ill-gotten gains. Ironic, really, for while Mafia Island and its surrounding archipelago has nothing to do with a society of secretive Sicilian criminals, it does indeed contain a hidden treasure-trove, its flashing gems hidden in the coral reefs that run the length of the island, from Ras Mkumbi at the northern tip to the islets strewn in the south.

Lapping the largely uninhabited archipelago that lies 200km (124 miles) south of Zanzibar, Mafia Marine Park's waters hold some of the richest reefs in the world, with an extraordinary variety of hard and soft corals and more than 400 species of fish flitting along its shallow reefs and their plummeting walls. Better still, with a grand total of six accommodations options in the entire archipelago, diving these clear waters is a far more exclusive experience than in Zanzibar or even Pemba. Whether it's swimming alongside a whale shark, exulting at the exquisite hues of a butterfly fish, or trailing a rare green turtle, you will savor what is tantamount to a religious experience in relative solitude.

When you've finished exploring this hidden world, there is little more satisfying then lying back on your dhow, listening to the snap of the wind grabbing the unfurled sailcloth and the rhythmical slap of water as the bow carves its way back to shore. As the sinking sun turns the horizon into a vast burning ember, one wonders what one ever found fault with in the world.

But the archipelago is more than just a magical dive site -- for centuries, Mafia played a key role in the East African trading routes that linked Zanzibar with Kilwa, the gold- and slave-trading city-state on the mainland's southern coast. The earliest-known settlement on Mafia is thought to have been built in the 11th century at Ras Kisimani, where coins predating the 1300s and minted in Kilwa, China, Mongolia, India, and Arabia have been uncovered, followed by Kua, a settlement established on nearby Juani Island in the 13th century. Little is left of the medieval settlement of Ras Kisimani, destroyed by a cyclone, but Kua's ruins still stand on Juani Island -- a wonderfully atmospheric place, the crumbling walls of its palace now in the firm grip of fig tree roots, its only minions wild pig and antelope.

Naturally, these ruins cannot compete with the vibrancy of Zanzibar's Stone Town, but if you're looking for privacy and seclusion, Mafia offers a true respite: a tropical island paradise that lies a mere half-hour flight from Dar es Salaam, but trailing 50 years behind the 21st century, with nothing to distract you from your reverie but the rustle of palm trees or the far-off murmur of fisherman heading out to sea on their dhows. Untouched, remote, and serene, it's the ultimate romantic hideaway and the perfect end to a land-based safari.

What Century Are We In? -- The sense of stepping outside time starts as you descend to meet the palm-lined sandy clearing that passes for a runway. The pilot taxis up to a whitewashed shed, juddering to a halt near a neatly placed row of white plastic chairs behind a hand-painted sign that reads DEPARTURE LOUNGE. Bumping along dirt tracks in a battered Series 1 Land Rover, past villages and fecund fields and waving children, it is as if you've traveled back 50 years.