Piaski is a small village on the far-east end of the Polish coast, close to Russian border, 12 km east of Krynica Morska.
This is probably the longest naturist beach in Poland and it's possible to be naked all along the coast for 5 km or more.

You can park on one of the forest parking places along the road from Krynica Morska and walk to the beach.
Alternatively, you can walk from Piaski westwards, about 2 km from the village the nude section starts. The sea here is not so clean.