مَلَأْنَا الْبَرَّ حَتَّى ضَاقَ عَنَّا
We filled the land until it felt too narrow.
وَمَاءَ الْبَحْرِ نَمْلَؤُهُ سَفِينَا
We filled the sea with our ships.
ImageRhetorical effectLand becomes too narrowExaggerated size of the peopleSea fills with shipsExaggerated reach and power
Together, land and sea create a figure of total spatial reach. The construction is intentional mubālaghah, hyperbole.