The submarine Rumble IV volcano was thought to have been active from April to December 1966, based on hydrophone signals (Kibblewhite, 1967), but later evidence indicated that the hydrophone array had been damaged and the signals originated from Rumble III (Hall, 1985). Fresh, glassy andesitic lava was dredged from the summit in 1992 during a New Zealand Oceanographic Institute cruise, and gas bubbles were acoustically detected rising from Rumble IV.