When a sponge is placed in a container full of water, it tends to suck up water, and get wet, even above the remaining water level. How does this water get sucked up against gravity?
This happens due to effect called capillarity, that causes water to move up narrow cylindrical channels. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity.
The pores of sponge are sufficiently narrow that the cohesion between water molecules and adhesion between the water and the surfaces of the pores combine to lift the water into the pores.Specifically the adhesion between the sponge fibers and the water molecules is high enough that water prefers to be touching the sponge more than other water molecules and so there is a tendency for it to "creep" up the sponge. In short, the capillary action, due to the pressure of cohesion and adhesion causes the liquid to work against gravity.