Demarcation between seawater and river water

۞ وَهُوَ ٱلَّذِى مَرَجَ ٱلْبَحْرَيْنِ هَٰذَا عَذْبٌۭ فُرَاتٌۭ وَهَٰذَا مِلْحٌ أُجَاجٌۭ وَجَعَلَ بَيْنَهُمَا بَرْزَخًۭا وَحِجْرًۭا مَّحْجُورًۭا

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.

أَمَّن جَعَلَ ٱلْأَرْضَ قَرَارًۭا وَجَعَلَ خِلَٰلَهَآ أَنْهَٰرًۭا وَجَعَلَ لَهَا رَوَٰسِىَ وَجَعَلَ بَيْنَ ٱلْبَحْرَيْنِ حَاجِزًا ۗ أَءِلَٰهٌۭ مَّعَ ٱللَّهِ ۚ بَلْ أَكْثَرُهُمْ لَا يَعْلَمُونَ

Or, Who has made the earth firm to live in; made rivers in its midst; set thereon mountains immovable; and made a separating bar between the two bodies of flowing water? (can there be another) god besides Allah? Nay, most of them know not.

مَرَجَ ٱلْبَحْرَيْنِ يَلْتَقِيَانِ

He has let free the two bodies of flowing water, meeting together:

بَيْنَهُمَا بَرْزَخٌۭ لَّا يَبْغِيَانِ

Between them is a Barrier which they do not transgress: