The Dead Sea is technically a lake.
Why it is true
The Dead Sea, between Israel and Jordan, is actually a salt lake with no outlet to the sea. With about 9.6 times more salt than the ocean, its density is so high that people float easily.
Source: USGS
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This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.