Mention Cambodia to a reasonably worldly traveler and she’ll invariably picture Angkor Wat, the sprawling temple complex in the jungle’s depths. Tourists tend to squeeze the millennia-old site into a grander tour of Southeast Asia, their sole whistle-stop in the country. But for a 21st-century perspective on Cambodia’s assets, you’d be wise to look to the coastline, which unfurls some 275 miles between Thailand and Vietnam. Over the past few years, the southern stretch, dotted with islands, has been morphing from bucolic backwater into a bona fide beach destination, with resorts rapidly materializing. The area’s main gateway is Sihanoukville, a port city named for a former king. An increasing number of regional flights bring in a hodgepodge of sunseekers—weekenders from the capital Phnom Penh, European tourists on package holidays and backpackers looking to disconnect on the beach. Not too long ago, this small seaside city had the languor of a sleepy beach town. Now, casinos with names like Wisney World dot its blocks, the constant whine of grinders and circular saws backdrops conversation and new construction is swallowing up public beaches. Fortunately, you needn’t stay long: High-speed ferries deliver visitors to nearby islands and the hotels that line their powdery, more meditative beaches.