A long, graceful bay protected by a coral reef is Kailua’s delight. The nearly 4-mile-long stretch of ivory sand is made for strolling, and the weather and wave conditions can be just about perfect for swimming, kayaking, windsurfing and kitesurfing. None of this has gone unnoticed. Decades ago expatriates from the mainland bought up cottages crowded into the little neighborly lanes; the ones near the beachfront were often replaced with megahouses. South along the shore lies the exclusive enclave of Lanikai, with million-dollar views – and mansions to match.