Allah tells us how He has subjected the seas, with their waves lapping the shores, and how He blesses His servants by subjecting the seas for them so that they may travel on them, and by putting fish and whales in them, by making their flesh permissible to eat - whether they are caught alive or dead - at all times, including when people are in a state of Ihram. He has created pearls and precious jewels in the oceans, and made it easy for His servants to recover ornaments that they can wear from the ocean floor. He made the sea such that it carries the ships which plow through it. He is the One Who taught mankind to make ships, which is the inheritance of their forefather Nuh. He was the first one to travel by ship, he was taught how to make them, then people took this knowledge from him and passed it down from generation to generation through the centuries, so that they could travel from country to country and from place to place, bringing goods from here to there and from there to here. Thus Allah says:
(that you may seek from His bounty and that you may perhaps be grateful.) - for His bounty and blessings. Then Allah mentions the earth and how He placed in it mountains standing firm, which make it stable and keep it from shaking in such a manner that the creatures dwelling on it would not be able to live. Hence Allah says,
(And the mountains He has fixed firmly.) (79: 32).
(and rivers and roads) meaning He has made rivers which flow from one place to another, bringing provision for His servants. The rivers arise in one place, and bring provision to people living in another place. They flow through lands and fields and wildernesses, through mountains and hills, until they reach the land whose people they are meant to benefit. They meander across the land, left and right, north and south, east and west - rivers great and small - flowing sometimes and ceasing sometimes, flowing from their sources to the places where the water gathers, flowing rapidly or moving slowly, as decreed by Allah. There is no god besides Him and no Lord except Him. He also made roads or routes along which people travel from one land or city to another, and He even made gaps in the mountains so that there would be routes between them, as He says:
(And We placed broad highways for them to pass through.) 21:31
(And landmarks) meaning, signs like great mountains and small hills, and so on, things that land and sea travelers use to find their way if they get lost.
(and by the stars (during the night), they (mankind) guide themselves.) meaning, in the darkness of the night. This was the opinion of Ibn `Abbas.
Then Allah tells us of His greatness, and that worship should be directed to Him alone, not to any of the idols which do not create but are rather themselves created. Thus He says
(Is then He, Who creates, the same as one who does not create Will you not then reflect)(16:17). Then He shows His servants some of the many blessings He granted for them, and the many kinds of things that He has done for them. He says;
(And if you would try to count the favors of Allah, you would never be able to count them. Truly, Allah is Forgiving, Most Merciful.) (16:18) meaning that He pardons and forgives them. If He were to ask you to thank Him for all of His blessings, you would not be able to do so, and if He were to command you to do so, you would be incapable of it. If He punishes you, He is never unjust in His punishment, but He is Forgiving and Most Merciful, He forgives much and rewards for little. Ibn Jarir said: "It means that Allah is Forgiving when you fail to thank Him properly, if you repent and turn to Him in obedience, and strive to do that which pleases Him. He is Merciful to you and does not punish you if you turn to Him and repent."