Vouliagmeni

Here Lake Vouliagmeni and this shows why the place is named as such... in the 4th C the mountain sunk into a sinkhole and this lake (full of minerals) emerged... the water run deep and far under the rock/hills of Attiki).

It's walking distance from my friends home, but I never knew this spot with natural cause gave name to this Rivièra like suburb of Athens.