Human impacts on the global ocean are increasing in scale and scope. As we learn more about climate change, plastic pollution, deep sea mining, and overfishing we see more clearly that these impacts alter our relationship with the ocean. Around the world, communities of people are working together to observe, understand, and act to sustain ocean habitats. In her address to IIEA, Tessa Hill, author of At Every Depth, discusses our growing knowledge about the ocean and the changes that threaten it. The discussion provides an overview of the major themes and lessons from the book, and how they apply to people who are working to protect marine environments on a local, national, and international level.  About the Speaker:  Dr Tessa Hill is a Professor in the Earth & Planetary Sciences Department, and Associate Vice Provost for Public Scholarship and Engagement at UC Davis. Dr Tessa Hill is a Professor in the Earth & Planetary Sciences Department, and Associate Vice Provost for Public Scholarship and Engagement at UC Davis. She holds a Ph.D. in Marine Science from UC Santa Barbara (2004). Her research interests include climate change, both past and present, and understanding the response of marine species to environmental perturbation.  She is part of the Bodega Ocean Acidification Research (BOAR) group at Bodega Marine Laboratory, which aims to understand the impacts of ocean acidification and partner with local community groups to address these impacts. Tessa is a Fellow of the American Association for the Advancement of Science and the California Academy of Sciences. Tessa’s work has been featured in a variety of media outlets including National Public Radio, Al Jazeera, and New York Times. She was the recipient of the Rachel Carson Lecture from the American Geophysical Union in 2023. She is co-author of At Every Depth: Our Growing Knowledge of the Changing Oceans (Columbia, 2024).