Translation:

70. Were it Our Will We could make it salt (and unpalatable): then why do ye not give thanks?

Notes (Tafseer)

5253. The wonder of the two streams of water, one sweet and the other salt, constantly mingling, and yet always separate, is referred to more than once. The never-ending circuit is established by streams and rivers mingling with the ocean, the ocean sending forth mists and steam through a process of evaporation which forms clouds, and the clouds by condensation pouring forth rain to feed the streams and rivers again: see notes 3111-2 to xxv. 53, and n. 5185 to lv. 19, and the further references given there.