ok so there should be a rare chance that you go to excavate a tank and its partially in the water, covered in mud and bushes and you are required to clean it and remove the brush with cutters to see what it is have found. after you clean it off to discover its a panzer 4 D and you have discovered the "Panzer of the Lake" you ask it for some wisdom and accept it gladly before excavating it and restoring it in the shop.

you can call the achievement "what is your wisdom?" or 'Panzer of the Lake/River"

here is the youtube video for reference.

https://www.youtube.com/watch?v=RO58B6LcTfM