The Empty Quarter (Rub' al Khali) is a vast, hyper-arid sand desert, the largest contiguous sand desert in the world. Visiting typically requires a guided tour due to the harsh environment, lack of marked trails, and potential dangers. Accessibility is very limited, requiring specialized vehicles and experienced drivers to navigate the dunes. Solo travel is strongly discouraged. The best time to visit is during the cooler months (October to April) to avoid extreme heat. Costs vary widely depending on the tour operator and duration, but expect to pay a significant amount for a multi-day excursion. A typical visit lasts several days to explore different areas of the desert. Be prepared for basic camping conditions and limited facilities.