No, St. Maarten is not part of the US Virgin Islands. While it is located in the same Caribbean region, its political identity is entirely different. The island is uniquely divided into two distinct territories: the southern Dutch side, known as Sint Maarten, is an autonomous country within the Kingdom of the Netherlands; the northern French side, Saint-Martin, is an overseas collectivity of France. In contrast, the US Virgin Islands (USVI) consist of St. Thomas, St. Croix, and St. John, which are territories of the United States. This distinction is important for travelers in 2026 because while US citizens can visit the USVI with just a birth certificate on "closed-loop" cruises, visiting St. Maarten/Saint-Martin typically requires a valid passport. The island is a fascinating "two-nation" destination where you can cross a border with virtually no formalities, moving from the high-energy, casino-filled Dutch side to the relaxed, culinary-focused French side in just a few minutes by car.