The short answer
The Quran says Allah released two bodies of water, one fresh and sweet and one salty and bitter, and placed between them a barrier (barzakh) so that neither overwhelms the other. The commentators explain it as the meeting of rivers with the salty sea, with each keeping its nature by Allah's power, as a sign and a blessing.
Allah says: "It is He who has released [simultaneously] the two seas, one fresh and sweet and one salty and bitter, and He placed between them a barrier and prohibiting partition" 1. In Surah ar-Rahman: "He released the two seas, meeting [side by side]. Between them is a barrier [so] neither of them transgresses" 2.
What are the "two seas"? The Arabic bahr can mean any large body of water. As-Sa'di explains that the fresh "sea" is the rivers flowing over the land, and the salty one is the sea, and that the barrier keeps them from mixing in a way that would destroy the benefit of each 3. Al-Mukhtasar says the barrier prevents each from transgressing on the other "so that the sweet remains sweet and the salty remains salty" 4. Ibn Kathir says the sweet water is that of rivers, springs and wells, and explains the barrier as a partition of dry land 8.
Both are blessings. "Not alike are the two bodies of water... from each you eat tender meat and extract ornaments which you wear, and you see the ships plowing through [them]" 5. From both emerge pearls and coral 2.
The barrier also appears in a list of signs that point to Allah alone: He made the earth a stable ground with rivers and mountains, "and placed between the two seas a barrier. Is there a deity with Allah?" 6
Is this a scientific claim? Where rivers flow into the sea, fresh and salt water often do not blend at once: saltiness changes gradually across a transition zone. Some modern readers see a parallel with the verse, but the verses do not describe salinity or density, so this site does not present them as a scientific miracle. Be wary, too, of viral photos of "two seas that never mix"; the meaning of the verses does not depend on them.
The practical point is gratitude. The water we drink is fresh because Allah keeps it so. "If We willed, We could make it bitter, so why are you not grateful?" 7
Two seas released, fresh and salty, with a barrier and partition between them.
۞وَهُوَ ٱلَّذِي مَرَجَ ٱلۡبَحۡرَيۡنِ هَٰذَا عَذۡبࣱ فُرَاتࣱ وَهَٰذَا مِلۡحٌ أُجَاجࣱ وَجَعَلَ بَيۡنَهُمَا بَرۡزَخࣰ ا وَحِجۡرࣰ ا مَّحۡجُورࣰ ا ٥٣
And it is He who has released [simultaneously] the two seas, one fresh and sweet and one salty and bitter, and He placed between them a barrier and prohibiting partition
Two seas meet with a barrier neither transgresses; pearls and coral come from both.
مَرَجَ ٱلۡبَحۡرَيۡنِ يَلۡتَقِيَانِ ١٩ بَيۡنَهُمَا بَرۡزَخࣱ لَّا يَبۡغِيَانِ ٢٠ فَبِأَيِّ ءَالَآءِ رَبِّكُمَا تُكَذِّبَانِ ٢١ يَخۡرُجُ مِنۡهُمَا ٱللُّؤۡلُؤُ وَٱلۡمَرۡجَانُ ٢٢
19 He released the two seas, meeting [side by side] 20 Between them is a barrier [so] neither of them transgresses 21 So which of the favors of your Lord would you deny 22 From both of them emerge pearl and coral
أي: وهو وحده الذي مرج البحرين يلتقيان البحر العذب وهي الأنهار السارحة على وجه الأرض والبحر الملح وجعل منفعة كل واحد منهما مصلحة للعباد، { وَجَعَلَ بَيْنَهُمَا بَرْزَخًا } أي: حاجزا يحجز من اختلاط أحدهما بالآخر فتذهب المنفعة المقصودة منها { وَحِجْرًا مَحْجُورًا } أي: حاجزا حصينا.
Between them is a barrier that prevents each one of them from transgressing over the other so that the sweet remains sweet and the salty remains salty.
The two bodies of water differ, yet both give food, ornaments and routes for ships.
وَمَا يَسۡتَوِي ٱلۡبَحۡرَانِ هَٰذَا عَذۡبࣱ فُرَاتࣱ سَآئِغࣱ شَرَابُهُۥ وَهَٰذَا مِلۡحٌ أُجَاجࣱۖ وَمِن كُلࣲّ تَأۡكُلُونَ لَحۡمࣰ ا طَرِيࣰّ ا وَتَسۡتَخۡرِجُونَ حِلۡيَةࣰ تَلۡبَسُونَهَاۖ وَتَرَى ٱلۡفُلۡكَ فِيهِ مَوَاخِرَ لِتَبۡتَغُواْ مِن فَضۡلِهِۦ وَلَعَلَّكُمۡ تَشۡكُرُونَ ١٢
And not alike are the two bodies of water. One is fresh and sweet, palatable for drinking, and one is salty and bitter. And from each you eat tender meat and extract ornaments which you wear, and you see the ships plowing through [them] that you might seek of His bounty; and perhaps you will be grateful
Allah placed a barrier between the two seas; is there a deity with Allah?
أَمَّن جَعَلَ ٱلۡأَرۡضَ قَرَارࣰ ا وَجَعَلَ خِلَٰلَهَآ أَنۡهَٰرࣰ ا وَجَعَلَ لَهَا رَوَٰسِيَ وَجَعَلَ بَيۡنَ ٱلۡبَحۡرَيۡنِ حَاجِزًاۗ أَءِلَٰهࣱ مَّعَ ٱللَّهِۚ بَلۡ أَكۡثَرُهُمۡ لَا يَعۡلَمُونَ ٦١
Is He [not best] who made the earth a stable ground and placed within it rivers and made for it firmly set mountains and placed between the two seas a barrier? Is there a deity with Allah? [No], but most of them do not know
Allah sends down the water you drink and could make it bitter.
أَفَرَءَيۡتُمُ ٱلۡمَآءَ ٱلَّذِي تَشۡرَبُونَ ٦٨ ءَأَنتُمۡ أَنزَلۡتُمُوهُ مِنَ ٱلۡمُزۡنِ أَمۡ نَحۡنُ ٱلۡمُنزِلُونَ ٦٩ لَوۡ نَشَآءُ جَعَلۡنَٰهُ أُجَاجࣰ ا فَلَوۡلَا تَشۡكُرُونَ ٧٠
68 And have you seen the water that you drink 69 Is it you who brought it down from the clouds, or is it We who bring it down 70 If We willed, We could make it bitter, so why are you not grateful
And had We willed, We would have raised a warner in every town (51)So obey not the disbelievers, but strive against them with the utmost endeavor with it (52)And it is He Who has let free the two seas, this is palatable and sweet, and that is salty and bitter; and He has set a barrier and a complete partition between them (53)And it is He Who has created man from water, and has appointed for him kindred by blood, and kindred by marriage. And your Lord is Ever All-Powerful to do what He wills (54) The Universality of the Prophet's Message, How He Was Supported in His Mission and Allah's Blessings to Mankind Allah says: وَلَوْ شِئْنَا لَبَعَثْنَا فِي كُلِّ قَرْيَةٍ نَّذِيرًا (And had We willed, We would have raised a warner in every town.) 'Calling them to Allah, but We have singled you out, O Muhammad, to be sent to all the people of earth, and We have commanded you to convey the Qur'an,' لِأُنذِرَكُم بِهِ وَمَن بَلَغَ (that I may therewith warn you and whomsoever it may reach)(6:19). وَمَن يَكْفُرْ بِهِ مِنَ الْأَحْزَابِ فَالنَّارُ مَوْعِدُهُ (but those of the sects that reject it, the Fire will be their promised meeting place)(11:17). لِّتُنذِرَ أُمَّ الْقُرَىٰ وَمَنْ حَوْلَهَا (that you may warn the Mother of the Towns and all around it)(42:7). قُلْ يَا أَيُّهَا النَّاسُ إِنِّي رَسُولُ اللَّهِ إِلَيْكُمْ جَمِيعًا (Say: "O mankind! Verily, I am sent to you all as the Messenger of Allah...")(7:158). In the Two Sahihs (it is reported that the Prophet said:) بُعِثْتُ إِلَى الْأَحْمَرِ وَالْأَسْوَدِ (I have been sent to the red and the black.) And: وَكَانَ النَّبِيُّ يُبْعَثُ إِلَى قَوْمِهِ خَاصَّةً، وَبُعِثْتُ إِلَى النَّاسِ عَامَّةً (...A Prophet would be sent to his own people, but I have been sent to all of mankind.) Allah says: فَلَا تُطِعِ الْكَافِرِينَ وَجَاهِدْهُم بِهِ (So obey not the disbelievers, but strive hard against them with it.) meaning, with the Qur'an. This was the view of Ibn 'Abbas. جِهَادًا كَبِيرًا (with the utmost endeavour.) This is like the Ayah, يَا أَيُّهَا النَّبِيُّ جَاهِدِ الْكُفَّارَ وَالْمُنَافِقِينَ (O Prophet! Strive hard against the disbelievers and the hypocrites,)(9:73) وَهُوَ الَّذِي مَرَجَ الْبَحْرَيْنِ هَٰذَا عَذْبٌ فُرَاتٌ وَهَٰذَا مِلْحٌ أُجَاجٌ (And it is He Who has let free the two seas, this is palatable and sweet, and that is salty and bitter;) means, He has created the two kinds of water, sweet and salty. The sweet water is like that in rivers, springs and wells, which is fresh, sweet, palatable water. This was the view of Ibn Jurayj and of Ibn Jarir, and this is the meaning without a doubt, for nowhere in creation is there a sea which is fresh and sweet. Allah has told us about reality so that His servants may realize His blessings to them and give thanks to Him. The sweet water is that which flows amidst people. Allah has portioned it out among His creatures according to their needs; rivers and springs in every land, according to what they need for themselves and their lands. وَهَٰذَا مِلْحٌ أُجَاجٌ (and that is salty and bitter;) meaning that it is salty, bitter and not easy to swallow. This is like the seas that are known in the east and the west, the Atlantic Ocean and the Straits that lead to it, the Red Sea, the Arabian Sea, the Persian Gulf, the China Sea, the Indian Ocean, the Mediterranean Sea, the Black Sea and so on, all the seas that are stable and do not flow, but they swell and surge in the winter and when the winds are strong, and they have tides that ebb and flow. At the beginning of each month the tides ebb and flood, and when the month starts to wane they retreat until they go back to where they started. When the crescent of the following month appears, the tide begins to ebb again until the fourteenth of the month, then it decreases. Allah, may He be glorified, the One Whose power is absolute, has set these laws in motion, so all of these seas are stationary, and He has made their water salty lest the air turn putrid because of them and the whole earth turn rotten as a result, and lest the earth spoil because of the animals dying on it. Because its water is salty, its air is healthy and its dead are good (to eat), hence when the Messenger of Allah was asked whether sea water can be used for Wudu', he said: هُوَ الطَّهُورُ مَاؤُهُ، الْحِلُّ مَيْتَتُهُ (Its water is pure and its dead are lawful.) This was recorded by Malik, Ash-Shafi'i and Ahmad, and by the scholars of Sunan with a good [Jayyid] chain of narration. وَجَعَلَ بَيْنَهُمَا بَرْزَخًا وَحِجْرًا (and He has set a barrier and a complete partition between them.) meaning, between the sweet water and the saltwater. بَرْزَخًا (a barrier) means a partition, which is dry land. وَحِجْرًا مَّحْجُورًا (and a complete partition) means, a barrier, to prevent one of them from reaching the other. This is like the Ayat: مَرَجَ الْبَحْرَيْنِ يَلْتَقِيَانِ - بَيْنَهُمَا بَرْزَخٌ لَّا يَبْغِيَانِ - فَبِأَيِّ آلَاءِ رَبِّكُمَا تُكَذِّبَانِ (He has let loose the two seas meeting together. Between them is a barrier which none of them can transgress. Then which of the blessings of your Lord will you both deny)(55:19-21) أَمَّن جَعَلَ الْأَرْضَ قَرَارًا وَجَعَلَ خِلَالَهَا أَنْهَارًا وَجَعَلَ لَهَا رَوَاسِيَ وَجَعَلَ بَيْنَ الْبَحْرَيْنِ حَاجِزًا ۗ أَإِلَٰهٌ مَّعَ اللَّهِ ۚ بَلْ أَكْثَرُهُمْ لَا يَعْلَمُونَ (Is not He Who has made the earth as a fixed abode, and has placed rivers in its midst, and placed firm mountains therein, and set a barrier between the two seas Is there any god with Allah Nay, but most of them know not!)(27:61) وَهُوَ الَّذِي خَلَقَ مِنَ الْمَاءِ بَشَرًا (And it is He Who has created man from water,) means, He created man from a weak Nutfah, then gave him shape and formed him, and completed his form, male and female, as He willed. فَجَعَلَهُ نَسَبًا وَصِهْرًا (and has appointed for him kindred by blood, and kindred by marriage.) in the beginning, he is someone's child, then he gets married and becomes a son-in-law, then he himself has sons-in-law and other relatives through marriage. All of this comes from a despised liquid, Allah says: وَكَانَ رَبُّكَ قَدِيرًا (And your Lord is Ever All-Powerful to do what He wills.)
This answer was compiled with the help of AI, using only the verified texts shown here. Every reference links to its source. If you find a mistake, please report it. Updated 2026-09-24