Much experimental and theoretical work has been done on the collapse or bursting of vapour bubbles onto solid surfaces in liquids, and it is generally held that this is also the underlying cause of surface damage (“cavitation” damage). However, due to experimental difficulties, much less work has been done on the time-evolution of bubbles and cavities in thin liquid films, e.g. in thin lubricating films during shear. Thus, the intuition gained from experiments on, for example, hydrofoils in water tunnels, may not apply to tribological situations. We have used the surface forces apparatus technique to observe, at the submicroscopic level, the rapid growth and disappearance of vapour cavities between two moving surfaces while simultaneously monitoring their effects on the deformations and wear of the surfaces. We find that under these conditions the inception of cavities is a much more violent event than their collapse. The sudden nucleation and growth of cavities is associated with the relaxation of high local stresses on nearby surfaces, and it is at this point that damage occurs rather than during the much smoother subsequent collapse of cavities. Time-lapse video photos taken during the life cycles of cavities are presented. These clearly show the highly complex and inter-related processes that occur in the liquid and nearby surfaces during cavitation.