Beach
East Wynyard Beach
Tasmania, Australia · sea 18.2 °C at its warmest, in February

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020, sampled 16 km offshore, at the nearest open water cell of a 0.25° grid.
Wikipedia has no article about this beach yet. It is on the atlas from its Wikidata record and its photograph.
Questions
How warm is the sea at East Wynyard Beach?
The sea off East Wynyard Beach averages 18.2 °C at its warmest, in February, and 11.7 °C at its coolest. These are monthly means from NOAA's OISST v2.1 satellite and buoy record for 1991 to 2020, sampled at the beach's own coordinates.
When can you swim at East Wynyard Beach?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is East Wynyard Beach?
East Wynyard Beach is on the coast of Tasmania, Australia, at -40.9900, 145.7400. The map on this site flies straight to it.