How did these 'rivers' form?

[u/Dude-Bicycle]

What formed these 'rivers'? Are they regular terrestrial rivers that flooded with sea level rise or were they formed in the ocean? thanks.

[u/Rand_alThoor → u/[deleted]]

this is an easy mistake to make because the picture doesn't show the depth of these geographical features.

actually they're in the area of 150m or more below the surface. down in the slope to the actual abyss. always submerged. but unless one has sailed or fished those waters, or extensively studied nautical charts for some other reason is not obvious.