What is meant by the two seas that meet and have boundaries, as referred to in Verses 19-22 of Surat Ar-Rahman?

The magnificent creation of Allah concerning the two seas (fresh and salty) is mentioned in four Quranic verses: Al-Furqan/53, An-Naml/61, Fatir/12, and Ar-Rahman/19-21. Interpreters believe that the two seas refer to fresh rivers and salty seas, citing Allah's saying: ﴿This is palatable and sweet, and this is salty and bitter.﴾ As for the "barzakh" mentioned between them, scholars have two opinions: 1. The physical barzakh: This refers to the dry land and areas separating rivers and seas, as mentioned by Ibn Kathir and Al-Sa'di. 2. The metaphysical barzakh: This is an unseen barrier from Allah's power that prevents their mixing despite their meeting, attributed to the difference in density between the two waters, as stated by Ibn Ashour and Ibn Uthaymeen.

There is no contradiction between the two opinions, as both are correct and apply to the verses, and this is a matter of diversity in interpretation.