There's just Nidri beach which starts after the main strip of restaurants on the harbour. There's the first stretch and then more space and sunbeds on the longer stretch after the watersports. The sunbeds belong to hotels and restaurants but you can still hire them. The beach is about 150-200 metres away or less than 10 mins walk. The beach gets busy. It's preferable to see the quieter beaches by hiring a car or going on a boat trip. The Odysseia boat trip is fantastic. There are also buses, bus stop with shelter less than 5 mins walk. The bus timetable is online.