The deep sea is currently at the heart of the last remaining, big knowledge frontier. Information about the deep sea is critical to close the loop from oceans to near space. The breath of scales is large, but the challenges are mostly technological. Inhospitable and extreme environments are the obstacle, where the rules are radically different. For this project, the MSEAS team will develop and apply its expertise in multiscale physical-biogeochemical-acoustical ocean modeling and data assimilation, Bayesian inference and scientific machine learning, and principled optimal planning for coordinated fleets of AUVs, surface autonomous vehicles, UAVs and other aircrafts, and near space assets.