Volcanologist David A. Johnston writing field notes at Coldwater II observation station May 17, 1980, the evening before he was killed by the lateral blast of the Mount St. Helens eruption. Earlier in the day, Johnston had collected volcanic gas samples from a fumarole high on the unstable northern side of the volcano (see fig. 20.). This photograph was taken by Harry Glicken, who was relieved of his observer duties at Coldwater II by Johnston and who brought this film out of the area the night before the fatal eruption. Among those who lost their lives in the May 18, 1980, eruption of Mount St. Helens was an exceptional colleague, volcanologist David Johnston. David was special not only because he was the first member of the U.S. Geological Survey to die in a volcanic eruption but also because of his capabilities and his dedication to his science. He knew well the personal risks involved in studying active volcanoes. Yet, his belief in the need to better understand volcano behavior led him to vigorous service in the "front lines" at Mount St. Helens. Through it all, he displayed a rare combination of inventiveness and originality in his scientific observations and interpretations. On the morning of May 18, David was alone at the Coldwater II observation station, 5.7 miles from the mountain's summit, measuring the volcano's bulging northern side. He was among the first to see the beginning of the eruption and tried to send a warning to the control center. "Vancouver, Vancouver, this is it!," he shouted into his radio. Then, as the black, billowing front of the lateral blast raced toward him, he tried a second message, which was garbled by atmospheric disturbance from the eruption. Then-nothing. The lateral blast obliterated Coldwater II observation station. Ironically, the location was (and is again) considered to be much safer than some of the sites on the mountain itself that David and his colleagues visited regularly. We dedicate this report to David Johnston, an untimely loss to his science as well as to his friends. Photographs used to depict various events or features discussed in the text were selected, insofar as it was practical, to reflect the first occurrence or discussion of the specific event or feature. Better illustrations of several subjects, however, are provided by photographs that were not strictly equivalent in time. Other illustrations are enhanced by paintings by U.S.