This INSPIRE award is partially funded by the Cyber-Physical Systems Program in the Division of Computer and Network Systems in the Directorate for Computer and Information Science and Engineering, the Information and Intelligent Systems Program in the Division of Information and Intelligent Systems in the Directorate for Computer and Information Science and Engineering, the Computer Systems Research Program in the Division of Computer and Network Systems in the Directorate for Computer and Information Science and Engineering, and the Software and Hardware Foundations Program in the Division of Computing and Communications Foundations in the Directorate for Computer and Information Science and Engineering. Sound plays a vital role in the ocean ecosystem as many organisms rely on acoustics for navigation, communication, detecting predators, and finding food. Therefore, the 3D underwater soundscape, i.e., the combination of sounds present in the immersive underwater environment, is of extreme importance to understand and protect underwater ecosystems. This project is creating a transformative distributed ocean observing system for studying the underwater soundscape at revolutionary spatial (~100 meters) and temporal (~100 seconds) resolutions that is also able to simultaneously resolve small-scale ocean current flow. These breakthroughs are achieved using a distributed collective of small hydrophone-equipped subsurface floats, which utilize group management techniques and sensor fusion to understand the ocean soundscape in a Lagrangian manner. The ability to record soundscapes provides a novel sensing technology to understand the effects of sound on marine ecosystems and the role that sound plays for species development. Experiments off the coast of San Diego, CA, and a research campaign in the Cayman Islands provide concrete scientific studies that are tightly interwoven with the engineering research. Oceans are drivers of global climate, are home to some of the most important and diverse ecosystems, and represent a substantial contribution to the world's economy as a major source of food and employment. The technological and scientific advances in this project provide crucial tools to understand natural ocean resources, by studying soundscapes at spatio-temporal scales that were heretofore extremely burdensome and expensive to obtain.