Plume visualization is essential for unveiling the dynamics of hydrothermal systems. This paper introduces an interactive exploration tool, PlumeViz, designed to facilitate the extraction and visualization of multifaceted plume characteristics from data collected by a sonar device. The tool addresses the challenges posed by undersampled volume data and intricate plume structures by providing an interactive platform for plume identification, visual representation, and analysis. Key functionalities of PlumeViz encompass comprehensive plume evolution, plume feature extraction, and in-depth exploration of specific regions of interest. We demonstrate the efficacy of PlumeViz in visualizing hydrothermal plumes through a case study and a range of illustrative results.