Read and reflect on verse 3672 from Surah Faatir: [Easy is it for Him to create likeness and variety:] thus, the two great bodies of water [on earth] are not alike the one sweet, thirst-allaying, plea...
وَمَا يَسْتَوِي الْبَحْرَانِ هَٰذَا عَذْبٌ فُرَاتٌ سَائِغٌ شَرَابُهُ وَهَٰذَا مِلْحٌ أُجَاجٌ ۖ وَمِنْ كُلٍّ تَأْكُلُونَ لَحْمًا طَرِيًّا وَتَسْتَخْرِجُونَ حِلْيَةً تَلْبَسُونَهَا ۖ وَتَرَى الْفُلْكَ فِيهِ مَوَاخِرَ لِتَبْتَغُوا مِنْ فَضْلِهِ وَلَعَلَّكُمْ تَشْكُرُونَ
[Easy is it for Him to create likeness and variety:] thus, the two great bodies of water [on earth] are not alike the one sweet, thirst-allaying, pleasant to drink, and the other salty and bitter: and yet, from either of them do you eat fresh meat, and [from either] you take gems which you may wear; and on either thou canst see ships ploughing through the waves, so that you might [be able to] go forth in quest of some of His bounty, and thus have cause to be grateful.