Well, technically cavitation is the formation of the vapor
cavities in the first place as the pressure on the backside of a blade drops below the vapor point of water.
Root cavitation causes relatively large vapor cavities near the hub that collapse roughly once per revolution, making a beating sound. Root cavitation causes significant losses in efficiency, makes a lot of noise, and seriously erodes the prop over time (sometimes causing the loss of a blade).
Submarine propellers in the 1940s did not suffer from root cavitation as it was a well known phenomenon at that time. They did, however, suffer from tip-vortex cavitation, in which long thin vapor trails form in vortices at the blade tips (as seen in the pictures); this is the same effect you occasionally see at the tips of aircraft wings. Tip cavitation creates noise and erodes the prop, but far less than root cavitation. It also creates a distinctive swishing sound, once per blade per revolution.
Modern submarine propellers suffer from neither form of cavitation unless using full power at or near the surface...
