Hạ Long Bay, a UNESCO World Heritage site in Vietnam, is renowned for its stunning limestone karsts and emerald waters. Accessibility ranges from easy boat tours to more challenging kayaking and cave explorations. Solo travelers can easily join group tours, while guided visits offer deeper insights into the bay's geology and history. The best time to visit is typically from March to May or September to November to avoid peak tourist season and extreme weather. A day trip can cost between $50-$200, depending on the tour type, with typical visits lasting from a few hours to several days, including overnight cruises. Be sure to check weather forecasts and book tours in advance, especially during peak season.