Thane is a district in northern Maharashtra state in western India. As of 2011 it is the most populated district in the nation, with 11,054,131 inhabitants The headquarters of the district is the city of Thane. Other major cities in the district are Kalyan-Dombivli, Mira-Bhayander, Bhiwandi, Ulhasnagar, Ambarnath, Kulgaon-Badlapur, Dahanu, Shahapur, Wada, Palghar and Vasai-Virar. This is the third-most industrialised district in Maharashtra.
The district is situated between 18°42' and 20°20' north latitudes and 72°45' and 73°48' east longitudes. The area of the district is 9,558 km². The district is bounded by Pune and Ahmadnagar on the east, Nashik on the east and northeast, Valsad District of Gujarat state and Union Territory of Dadra and Nagar Haveli on the north. The Arabian Sea forms the western boundary, while it is bounded by Mumbai City District and Mumbai Suburban District on the southwest and Raigad District on the south.