The Maldives is 1,192 islands scattered across the Indian Ocean like a spilled pearl necklace. 200 are inhabited, about 150 are resort islands. The rest are sandbars, uninhabited specks of land where boats take you for picnics. This is where turquoise water is so clear it looks fake, where there's more life underwater than above, and where the concept of "beach" takes on an entirely new meaning.

For decades, the Maldives meant impossibly expensive holidays—overwater villas at $2,000 a night, seaplanes, champagne at sunset. But since the 2010s, everything changed: local islands opened to tourism...