No More Holes In Swamps

I feel like Swamp Biomes are little lacking with atmosphere and flora/vegetation, but one thing that i especially think needs to be improved are the holes as seen here (not the pond in background)

So the idea is not to remove the holes or water, but to fill them with new layer/slab like blocks, that can submerge under water. The blocks could possibly have similar behaviors to soul sand, slowing down player. So instead of deep gaps where you fall in they'll be basically puddles and mud that slow you down