Let me know when coastlines are made of smooth-sided materials with no percolation.
In a glacier, the water can’t flow. Just as you can’t drink an ice cube, a glacier barely has any effect on land, which is primarily sand.
Release that trapped water, it interacts with coastlines, dissolving them further than if the water stayed in the glacier.
That’s why: goodbye coastlines. Time to draw new maps.
As humans, whether the ocean is 5 miles deep or 4.9 mile deep wouldn’t make as much difference as that 0.1 mile of “new ocean floor” coming from the human habitable part.
littoral cell is what this part is called. I looked it up. Everything has a name.