The Next Great Island Escape? This Little-Known African Country

The under-the-radar island nation of São Tomé and Príncipe offers an enthralling mix of history and luxury beach resorts

THE VOLCANIC ROCKS pricked my feet and my legs shook as we clambered up the near-vertical shore of the Ilhéu de Santana, a tiny islet in the archipelago of São Tomé and Príncipe, floating in West Africa’s Gulf of Guinea. In my mind’s eye, I pictured my husband losing his grip, tumbling into the blue depth of the Atlantic, where, apart from our guide’s small motor boat, all I could see was a sole fisherman in a wooden dugout.

When we told friends and colleagues of our plan to escape South Africa’s winter for a one-week break...