The use of the space between the wave and the sky, and the contrast between the waves and the mountain in the background, carries the idea of waves rising as tall as mountains — and of the danger that approaches when you stand in a small boat before one.

“And of His signs are the ships in the sea, like mountains. If He wills, He can still the wind and they would remain motionless on its surface… or He could destroy them for what they have earned — but He pardons much.”
— Surah Ash-Shura (42:32–34)

“Your Lord is the One Who causes ships to sail for you through the sea so that you may seek His bounty. He is indeed Most Merciful to you.”
— Surah Al-Isra (17:66)

“It is He who enables you to travel on land and sea, until, when you are in ships and they sail with them by a good wind and they rejoice therein, there comes a storm wind and the waves surround them from every side, and they assume that they are overwhelmed; they call upon Allah, sincere to Him in religion…”
— Surah Yunus (10:22)