The Qur'an reveals an important property of seas that has only recently been discovered by oceanographers: the two seas meet, yet do not intermix due to surface tension, a physical force caused by the difference in the density of their waters. This remarkable phenomenon, despite having no knowledge of physics or oceanography, was revealed by the Qur'an centuries ago, demonstrating the insight and power of its teachings.

Note 64. Richard A. Davis, Principles of Oceanography, (Don Mills, Ontario: Addison-Wesley Publishing Company), 92-93.