Rostock is located nearly centrally on Mecklenburg-Vorpommern's Baltic Sea coast. The city is crossed by the Warnow.

The seaside part of Rostock, Rostock-Warnemünde, is about 16 km (10 mi) to the north of the historic city centre. The west and the southeast are the most densely populated parts of town. The overseas port is to the east of Rostock. Rostock stretches 21.6 km (13.4 mi) from the Baltic Sea to the south and 19.4 km (12.1 mi) from east to west.

Rostock is the largest city in the north German state Mecklenburg-Vorpommern. Rostock is located on the Warnow river; the quarter of Warnemünde 12 kilometres (7 miles) north of the city centre is directly located at the coast of the Baltic Sea.

Rostock is home to one of the oldest universities in the world, the University of Rostock founded in 1419.

The city territory of Rostock stretches for about 20 km (12 mi) along the Warnow to the Baltic Sea. The largest built-up area of Rostock is on the western side of the river. The eastern part of its territory is dominated by industrial estates and the forested Rostock Heath.