Terrestrial fluids, earthquakes and volcanoes: The Hiroshi Wakita Volume II is a special publication to honor Professor Hiroshi Wakita for his scientific contribution to science and commemorate his 10th anniversary as Emeritus Professor at The University of Tokyo. This second special issue of Pure and Applied Geophysics consists of 10 original contributions written by researchers from Japan, Germany, Italy, Costa Rica, Sweden, El Salvador, Turkey, USA, Greece, and Spain. The discussed subjects include research on earthquake-related hydrologic and geochemical observed temporal changes, diffuse degassing in active tectonic and volcanic settings, the observed changes on gas emission and temperature prior volcanic eruptions, magma degassing signature in the groundwater system of active volcanic, and the development of recent technology for continous monitoring of volcanic gases. The Hiroshi Wakita volume II will be useful to students and professional researchers who are interested in the role of terrestrial fluids in earthquakes and volcanic activity.