Alfred staggered where he stood, his legs sinking beneath him.

Its multiple legs sank firmly into sockets in the walls.

He felt himself fall, his legs sinking into deeper loose material beneath.

He succeeded, only to feel his legs sink deeper.

Her legs sank toward the bottom until her feet hit a soft, mossy foundation.

Her legs did not exactly sink into the surface; it was just that she could not climb.

Even as he looked, his lower legs sank into the puddle that had been his feet.

Her legs suddenly unsteady, Maura sank into a chair across from him.

Rain felt her legs weaken and sank on to the edge of the bed.

It was a fairly massive creature, so each leg sank into the dirt as it landed.