Does anyone know how to get to lake vouliameni from Athens using public transportation?
I see you have a few questions about public transit in Athens. I assume you haven't found the relevant websites yourself yet. Check out this handy guide. https://www.athenstransport.com/english/. Google Maps is also a handy option.
Use Metro to get to Elleniko station. From there Lake Vouliagmeni is reached by the 122 bus. Total journey about an hour (source Google Maps).