Aloha colleagues, On behalf of my co-authors, we are excited to share our recent open-access publication in Endangered Species Research: Parnell K, Merkens K, Huetz C, Charrier I, Robinson SJ, Pacini A, Bejder L (2024) Underwater soundscapes within critical habitats of the endangered Hawaiian monk seal: implications for conservation. Endangered Species Research 54:311–329. *https://doi.org/10.3354/esr01336* <https://doi.org/10.3354/esr01336> Abstract: Studying underwater soundscapes of critical habitats of marine mammals can provide valuable information on the acoustic environment utilized by sound-reliant animals. For the endangered Hawaiian monk seal (Neomonachus schauinslandi; HMS), the acoustic scene of their aquatic habitats is poorly understood. We measured ambient noise levels and characterized sound sources at four shallow critical habitats of the HMS. Broadband levels ranged from 107.8-123.4 dB re 1 µPa. Octave band levels showed diel patterns associated with biological and anthropogenic sources that mask HMS vocalizations. Biological sources dominated the soundscape at all sites. We opportunistically recorded two large-scale geophonic events: hurricane Douglas (Category 4) and a 6.2 magnitude earthquake. This study provides the first description of underwater soundscapes at critical habitats of the HMS across its expansive range. These measurements serve as a baseline for future studies to understand impacts of human activities on underwater soundscapes. The publication is open-access and is available here: www.int-res.com/articles/esr2024/54/n054p311.pdf Please reach out if you have any questions: keparnel@hawaii.edu Mahalo, Kirby Parnell -- Kirby Parnell, M.Sc. PhD Candidate, Marine Biology Graduate Program Marine Mammal Research Program University of Hawaiʻi Mānoa *https://www.mmrphawaii.org/kirbyparnell <https://www.mmrphawaii.org/kirbyparnell>*