It is He Who has let free the two bodies of flowing water: One palatable and sweet, and the other salt and bitter; yet has He made a barrier between them, a partition that is forbidden to be passed.
He has let free the two bodies of flowing water, meeting together. Between them is a Barrier which they do not transgress
Until recently no one quite knew what this actually meant. But thanks to advances in science we have now found out that there are indeed two seas, one salty and the other sweet but even though they meet they do not mix. This can be seen in the Strait of Gibraltar where the Atlantic Ocean and Mediterranean Sea meet.
Watch the following documentary which I THINK is from HarunYahya.com and the actual video where a ship crosses the two seas