Unsteadiness: You feel suddenly unsteady, light-headed, woozy or dizzy. This is sometimes accompanied by a feeling that you might faint or pass out. It also may feel as though you are walking on a boat, or that the floor seems to move up and down and it's hard to balance. You may also have difficulty placing your feet because your perception of the ground or floor may be incorrect. In some cases it may seem that even though you are standing on a firm floor, the floor may be vibrating or moving.