More on Boden-See from Infoplease:

• Boden-See - Boden-See The Lake of Constance; so called because it lies in the Boden, or low country at the foot ...
• Constance: meaning and definitions - Constance: Definition and Pronunciation
• Dictionary of Phrase and Fable: B - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "B"