Overview

(Verses 19 - 25)

Blessings in Seas and Rivers

We now turn back to the earth and its waters, which God has made in exact measure that determines quantity, type, how it runs and how it is used:

He has given freedom to the two great bodies of water, so that they may meet; yet between them is a barrier which they do not cross. Which, then, of your Lord's blessings do you both deny? Pearls and corals come from both. Which, then, of your Lord's blessings do you both deny? His are the lofty ships that sail like floating mountains through the seas. Which, then, of your Lord's blessings do you both deny? (Verses 19-25)

The two bodies of water, expressed in the Arabic text as the two seas', are in fact the salty bodies of water including seas and oceans and the unsalted ones or rivers. God left them free to run and to meet, but did not allow them to exceed their limits. Each will fulfil its own function. In between them there is a barrier of the same nature, which God has put in place. The quantities of water on earth are not the result of any coincidence; they are determined by exact measure. Salty waters cover three-quarters of the earth's surface and they are mostly connected, while dry land represents only about one quarter of the earth. This very large quantity of salty water is the amount needed to keep the earth's atmosphere clean and suitable for supporting life.
 
In spite of all the gaseous emanations from the earth of all the ages, most of them poisonous, the atmosphere remains practically uncontaminated and unchanging in its balanced relationship necessary to man's very existence. The great balance wheel is that vast mass of water, the sea.

From this great mass of water evaporation takes place because of the heat of the sun, and what evaporates comes back in the form of rain which is the source of sweet water in all its forms, the most important of which finds its way into rivers. The careful proportion of the vastness of the sea, the heat of the sun, the cold temperatures in the upper atmosphere and other climatic conditions produce rain that provides unsalted waters, which is the mainstay of life for plants, animals and man.

Almost all rivers end in the sea, transporting various salts and compounds from land to sea. Thus, rivers do not change the nature of sea water. Normally rivers run at a higher elevation than sea level. Thus, the sea does not encroach on a river's course, flooding it with salty water. Had that been the case, the nature of rivers would have altered and their function ceased. In between the two there is always this barrier which God has put in place, ensuring that these two water bodies continue to fulfil their respective natural functions. It is no wonder that all this is mentioned here as being among God's great blessings: "Which, then, of your Lord's blessings do you both deny?" (Verse 21)

The surah also adds here some of the blessings God has placed in these two bodies of water, some of which can easily be seen: "Pearls and corals come from both." (Verse 22) The pearl is originally formed by a mollusc animal.

Perhaps the pearl is one of the most marvellous wonders of the sea. The mollusc goes to the bottom of the sea inside its hard shell which keeps it safe from danger. It is different from other animals in form and life pattern. It has a fine, wonderful net, similar to that of a fisherman, which allows air, water and food to enter, but stops sand, stone and similarly unwanted objects. Below it is the mouths of the animal, each with four lips. Should a grain of sand or a small stone or a harmful organism get through the net, the mollusc immediately covers it with a sticky discharge which then solidifies to form a pearl. The size of the pearl differs according to the size of the foreign object that finds its way inside.'

Coral is among God's amazing creation. It is found in the sea at depths ranging from 5 to 300 metres. It fixes its lower edge to a rock or weeds, keeping its mouth at the top. Around its mouth it has several protrusions used to capture food. Should a little creature touch any of these protrusions, it is immediately paralysed and sticks to the protrusion, which then shrinks and bends towards the coral mouth where the paralysed prey is pushed through a small passage similar to man's oesophagus.

Coral reproduces itself by discharging reproductive cells which fertilize the eggs, and the baby coral will then stick itself to a stone or a weed, starting an independent life like its mother.

Another sign of God's wonderful creation is that corals reproduce in another way, producing extensions that remain stuck to the main body. Thus the coral tree is formed with a wide trunk and narrower branches that may become very fine. The coral tree can reach 30 centimetres in length. Coral concentrations differ in colour: some are orange, some are of red carnation colour, some emerald blue, and others pale and dusty in colour. Red coral is the solid stem that remains after the living part has died. Coral stone-like concentrations can form large colonies. One of these is a chain of coral rocks known as the Great Barrier Reef, to the north east of Australia. The reef is 1,350 miles long and 50 miles wide.

Man makes precious jewellery from both pearls and corals. God mentions both as part of His blessings and the surah adds here the usual comment: "Which, then, of your Lord's blessings do you both deny?" (Verse 23)
 
The surah then mentions the ships that sail through the sea, some of which are very large, looking like mountains: "His are the lofty ships that sail like floating mountains through the seas." (Verse 24) The surah refers to these floating ships as belonging to God. They indeed sail by God's will. Nothing keeps them afloat in the sea, through its waves and currents except God's care. Hence, they belong to Him. They remain among the great favours with which He blesses human life. They provide a means of livelihood, transportation and comfort that people cannot deny. Hence, the comment: "Which, then, of your Lord's blessings do you both deny?" (Verse 25)