Swollen polymer brushes are found in various applications including biomedical coatings where the brush provides stability against harsh environmental conditions and mediates interactions with the surroundings. The surface height fluctuations of planar polystyrene brushes (0.04-0.61 chains/nm(2)) highly swollen in toluene vapor are so strongly slowed by the tethering of the chains that they are unobservable in the current experimental window of length and time. This is the case despite the fact that the segmental dynamics of the brush chains should be very fast due to the substantial plasticization by the solvent. With respect to thermally stimulated fluctuations, the surfaces of these swollen brushes are solidlike on time scales and length scales pertinent to many practical applications.