Using a 2.5‐megacycle spherical focusing radiator, cavitation is produced in water at a location remote from any liquid‐solid interface. The cavitating region is localized in the high intensity core of the focal region, about one millimeter diameter by 10 millimeters long. A feather‐like cavitation burst is sporadically produced within the focal region. High speed camera studies show that the total duration of the burst is less than 3 milliseconds, and that the cavitation at any one point of the burst is completed in a matter of microseconds. The cavitating region propagates along the feather shaped burst from the quill end (nearest the radiator) to the tip end, at a velocity of 5 to 10 meters per second. It is believed that this velocity corresponds to that of the radiation pressure induced streaming velocity of the liquid along the axis, of the focal spot, and that a discrete, traveling, oscillating cavity initiates the surrounding cavitation. These sporadically produced cavitation bursts appear without other effects in degassed water. On the other hand, in aerated water identical appearing bursts produce noncollapsing air bubbles which blow off down stream (because of liquid streaming) providing there is no standing wave pattern present. In the presence of standing waves many of the bubbles are trapped in the standing wave pattern until they grow too large (by accumulation of other bubbles) when they again blow down stream. Slides showing the nature of these phenomena will be exhibited.