Why does underwater noise matter?
Noise travels faster and father underwater than it does on land. This can have significant effects on some of the Puget Sound’s most beloved species, including the survival of some endangered species. Marine animals, such as marine mammals, fish, and birds, rely heavily on sound for survival. Underwater noise can have especially harmful impacts on the Southern Resident orca who depend on echolocation to hunt their prey, navigate our waters, and communicate. In a loud environment, like the Puget Sound, this becomes increasingly difficult. Noise can also impact behavioral changes, reproduction challenges, and physical damage.
Underwater noise and vessel traffic have been identified as one of the top threats to the survival of the Southern Resident killer whales along with salmon availability and contamination of waterways.
What causes underwater noise?
Underwater noise can be from natural sources such as: waves, storms, and earthquakes. Or from human activities such as in-water construction, commercial/shipping vessels, reactional boating, and ferries.
How is the Port of Seattle helping quiet the Sound?
Reducing impacts on endangered species is a top priority of the Port of Seattle. Steps we have taken to reduce underwater noise are:
- Creation of an Underwater Noise Mitigation and Management Plan. The plan describes ways for the Port to reduce noise effects on sensitive species and best practices for in-water construction.
- Certification and annual reporting for Green Marine on underwater noise and other environmental performance indicators.
- Partnership with Quiet Sound. This organization has implemented a voluntary vessel slow down zone through the orca’s critical habitat. When boats slow down, the noise decreases as well!
- Communicating with industry partners and the public about underwater noise.
- Investing in shore power at cruise ship terminals to reduce noise from idling engines.
- Measuring baseline noise levels in Elliott Bay to help set future noise reduction goals.
Elliott Bay Underwater Noise Assessment Program
The Elliott Bay Underwater Noise Assessment Program (UNAP) started in July 2025 as part of the implementation of the Port of Seattle’s Underwater Noise Mitigation and Management Plan. The goal of this program is to better understand the baseline underwater noise levels in Elliott Bay. The Port of Seattle, with support from hydroacoustic experts, are measuring noise levels with two hydrophones, underwater sound recording devices, placed in Elliott Bay. Data will be collected over a two-year period so the Port can better understand how different weather conditions, seasonality, and vessel traffic impact the underwater soundscape.
- Phase I Underwater Noise Assessment Report
- Phase II Underwater Noise Assessment Program Design Report
- Phase II Quarterly Reports:
- Q3 2025
- Q4 2025 (Coming soon)
Learn more
- Reducing Impacts of Ships on Climate and Marine Life (2023)
- Quieting Underwater Noise to Protect Marine Life (2022)
- Port Invests in Research and Technology to Quiet the Sound (2022)
- Co-Chair Letter Urging Strong U.S. Action to Reduce International Maritime Greenhouse Gas Emissions and Underwater Noise (2021)
- Fresh Perspectives to Help Protect Orcas (2021)
- Shhh … A Quiet Sound Protects Orcas (2020)
- Startup Uses Technology to Promote Orca Conservation (2020)
- Port Gathers Diverse Maritime Interests to Protect Endangered Orcas by Reducing Ship Noise (2019)
Top photo credit: SRKW Breaching," NOAA, via Wikimedia Commons, Public Domain
