18:61
فَلَمَّا بَلَغَا مَجْمَعَ بَيْنِهِمَا نَسِيَا حُوتَهُمَا فَٱتَّخَذَ سَبِيلَهُۥ فِى ٱلْبَحْرِ سَرَبًا
falammā balaghā majmaʿa baynihimā nasiyā ḥūtahumā fa-ittakhadha sabīlahu fī l-baḥri saraban
but when they reached the place where the two seas meet, they had forgotten all about their fish, which made its way into the sea and swam away.
But when they reached the junction of the two seas, they forgot their fish, and it took its way through the sea as in a tunnel.