In 2025, oceanic research in the Gulf marked a significant milestone. The DEEPEND (Deep Pelagic Nekton Dynamics) research consortium completed the first of two 5-year funding phases from the NOAA RESTORE Science Program (NRSP) and its 10th anniversary as a collaborative entity (GoMRI: 2015-2020; NRSP Phase I). Over the past decade, DEEPEND has built the first long-term time-series of deep-pelagic (0-1500 m depth) fish, shrimp, and cephalopod populations in the Gulf. This work has cemented the deep Gulf’s standing as a global hotspot of deep-pelagic biodiversity. Faunal analyses have revealed scores of new records and new species in the deep Gulf. Population assessments revealed sharp persistent declines in abundance since 2011. Resource managers report that these trends parallel those in some managed/protected species that are dependent on deep-pelagic prey. Genomic data confirm reductions in genetic diversity among dominant taxa, both corroborating the decline and a consequence of it. Biogeochemical analyses reveal petrogenic contamination in the deep-pelagic fauna, a likely driver, as well as increasing levels of microplastic contamination with depth. Together, these findings indicate that the largest and most remote component of the Gulf ecosystem — the deep-pelagic domain — has indeed been altered by human activity. DEEPEND’s work will continue during NRSP Phase II, with faunal and genomic assessments paired with expanded high-resolution bioacoustic and contaminant analyses. New initiatives include the development of a DNA reference library for deep-pelagic animals, the creation of a comprehensive oceanic fish guide with more than 180 new records, and broadened analyses of the distribution of individuals and biomass in the open ocean domain. As always, we welcome in-depth collaboration with stakeholders and resource managers and hope that this work informs Gulf ecosystem use and management.