The compact city centre — Old Town, Cultural Quarter, West Quay, and the seafront — is walkable in about 25 minutes end to end. Most visitors will not need any transport beyond their feet for the main attractions.
For longer trips, buses run frequently on the main corridors. Bluestar and Unilink are the two main operators. A day pass is around £5 and covers most of the local network. Tickets are bought from the driver or via the app.
Taxis and ride-share (Uber operates) are easy enough in the centre. From the railway station to most central destinations is £5–8.
For the New Forest to the west and the Hythe ferry, the Town Quay ferry terminal is a five-minute walk from the medieval walls. The ferry to Hythe runs every 30 minutes and connects with the Hythe Pier Railway for a quick out-and-back trip across Southampton Water.