Pärnu is a coastal city in southwest Estonia and the principal city of the Pärnumaa (Pärnu County) region. It lies 128 kilometres south of Tallinn and 176 kilometres west of Tartu, on Pärnu Bay, an inlet of the Gulf of Riga in the Baltic Sea. The Pärnu River, Estonia's second-longest, flows through the city and empties into the gulf at the city centre.
The city is known as a resort destination, with a white-sand beach, a seaside promenade and the renovated Rannapark, a protected park more than a century old. About one fifth of the city area is green space, including wooded areas, tree-lined alleys and parks. The Pärnu Coastal Meadow Nature Reserve covers 375 hectares across the Kesklinn, Mai, Raeküla and Vana-Pärnu districts, with roughly 250 hectares of semi-natural habitat, mostly coastal meadows grazed from spring to autumn by Highland cattle. Birdwatching towers stand at the Mai and Raeküla beaches.
The city is compact and navigable on foot or by bicycle, with more than 70 kilometres of cycling and walking routes. In 2020 it was named the Most Sustainable Tourism Destination in the Baltic Sea Region, and it holds a Green Destinations Silver-level recognition from 2023.