please provide clarification for the verse 24 40 in the Quran.

Asaalam o alaikum! I have been riddled with doubt over the Quran verse 24 40 and need clarification. I am confused about the section that states (interpretation of the meaning) “if he puts out his hand he can hardly see it”. This is confusing to me because the oceans darkness would prohibit you from seeing your hand at all as there is 0 light present within most of the ocean. I don’t understand why Allah AJ would use that example when there really is no light at the bottom of the sea. Please help me understand. Thank you!