Marsh, swamp, wetlands, bogs.
Soft wet ground is called "mud."
Quick Sand, YIKES!
The land that is soft and wet and yields to pressure is called marshland or a marsh. It is characterized by waterlogged soil and the growth of wetland plants. Marshes are found in coastal areas, river floodplains, and other low-lying areas with high water levels.
swamp
marsh
Wet and soft soil is called mud. It usually results from a combination of water and earth, creating a viscous mixture often found in wetlands, marshes, or after heavy rainfall.
In the ocean the sand and seaweed at the bottom of the water are very wet and moist. Its like silk (very soft). So the land at the bottom of the ocean is wet and full of moisture.
It is frozen silt called muck which is wet soft mud.
Marsh
It's called saliva.
Quick sand, bog and muskeg all have such properties.
a tract of soft wet land, commonly covered partially or wholly with water; a fen; a swamp; a morass. and there has another opinion that says---a plant (nartheeium ossifragum) with linear equitant leaves, and a raceme of small white flowers; -- called also bog asphodel in a broad sense marshy land is a place or track which is more slippery and dusty and wet by the growth of algy type plants.