Translation:Your vacations are more expensive than my house at the lake.
House on the lake should perhaps be added. It's a frequent way in US English to say 'house sitting right next to the lake'. Lake house is another way of saying that sort of place.
I'd say by or on would be a more common choice than at, from an American English perspective.
Der See means "the lake". Die See means "the sea, the ocean". It is less commonly used. German uses more often das Meer or der Ozean for the latter. Check out Bodensee and Nordsee on Google Maps and see if you can figure out which one is feminine and which one is masculine :)