Crystal Bay refers to several popular spots, most notably a stunning beach on Nusa Penida, Bali, known for clear waters, snorkelling, and sunsets, and also a well-known beach area on Koh Samui, Thailand (Silver Beach), offering resorts, food, and activities like diving. Other locations include a community near Lake Tahoe (Crystal Bay, NV/CA) and hotels in places like Puri, India, but the iconic tropical beach destinations are the main draws.