Vent Ejects Debris (IMAGE) University of Washington Caption West Mata is an elongated submarine volcano almost two miles long and 5,000 feet tall. There are two large eruptive vents at its summit, here the vent named Prometheus ejects gas, rocky debris and a shower of white sulphur. Credit NSF/NOAA Usage Restrictions Credit required License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.