25:53
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.
The Qurʾān refers to the existence of two bodies of water, one described as salty and the other as sweet. While some interpreters have understood this description as referring to the relationship between oceans and rivers, others argue that this interpretation is based on assumption rather than definitive textual evidence. The Qurʾān uses the Arabic term baḥr, which is commonly translated as “sea,” “ocean,” or “large body of water,” and frequently appears in singular or dual forms, suggesting deliberate linguistic precision. For instance, Qurʾān 27:61 refers to God as the One who “placed between the two seas a barrier,” while Qurʾān 25:53 describes God as releasing “two seas, one sweet and palatable and the other salty and bitter,” with a partition separating them (Qurʾān 25:53; 27:61). These verses raise interpretive questions regarding the identity of the two bodies of water and the nature of the barrier between them.
From the Qurʾānic description, one body of water is clearly salty and the other sweet. Modern scientific knowledge indicates that the world’s oceans are largely interconnected, forming a single global system of saline water, whereas rivers are numerous and geographically distinct. For this reason, some interpreters argue that the “sweet sea” mentioned in the Qurʾān cannot simply refer to rivers. Rivers do not form a single interconnected body of water, and most rivers eventually flow into the ocean, where their freshwater mixes with saltwater rather than remaining permanently separated by a fixed barrier. Furthermore, the Qurʾān commonly uses a different Arabic term, anhār, when referring specifically to rivers. In Qurʾān 35:12, for example, the text again contrasts two bodies of water—one sweet and one salty—while noting that both provide food and other benefits for human beings (Qurʾān 35:12).
Based on these linguistic and contextual observations, some commentators propose that the “sweet sea” may refer to extensive underground freshwater systems beneath the earth’s surface. These freshwater reservoirs, which include aquifers, springs, lakes, and wells, constitute significant bodies of water that are continually replenished through natural processes such as rainfall and the broader hydrological cycle. In this interpretation, Qurʾānic references to the earth’s capacity to hold and preserve water may be seen as relevant, such as in Qurʾān 77:25–26, which describes the earth as a place that gathers and contains both the living and the dead.
References:
Mirza, Said. Cosmology of the Qur’an: The Seven Skies and the Fixed Ground (p. 49-50). Menof God. Kindle Edition.