Translation of ridge in Spanish

So you have taken a German course in the Ghoete Institute. Well, I certainly learned something with you, and your German is already a lot better than last time. I think we really did it.
On the frozen lake, you can skate, but I would never dare it because it is far too dangerous. Who knows how thick the ice really is and how accurate the measurements are. It can break.
How long have you been practicing Spanish using this site and in which lesson are you now? I am now at vocabulary lesson number 3. It is still hard for me, but I'm quite new here and need to get better.