In 1974 the former City of Nynäshamn (itself instituted in 1946) was merged with Ösmo, from which it had been detached as a market town (köping) in 1911 and Sorunda, all in the Södertörn peninsula and adjacent islands.

[5] As all municipalities in Stockholm County Nynäshamn is served by the public transport system operated by SL.

There are a number of stations of Stockholm commuter rail as well as a bus network in the municipality.

The Draget Canal allows boats to traverse the municipality from west to east without needing to pass offshore of the Landsort peninsular.

Nynäshamn boasts sandy beaches, areas suitable for long walks, for riding horses and for bicycling, all popular activities.