Berlin

Germany

Not one of the top-notch sites, but very easy to reach by car. Nice "after-work" dive site :)

From Ritterfelddamm turn into Uferpromenade and follow the street for app. 200m. To your right you will spot a gate and beyond that a large lawn, leading to the waterfront. 
Just leave the car somewhere near the gate but DON'T BLOCK the gate! As this is an emergency "entrace" to the lake for the police and emergency physicians (your car will otherwise be towed - fee for being towed is app. 250$ in Germany)

Glienicker See is also known as Pferdekoppel.