The ocean has never been silent - waves crashing, seabirds calling, whales singing across vast distances. But in recent decades, a new kind of noise has taken hold: the relentless hum of ships. For many marine species, this growing wall of sound is more than a nuisance - it's a threat to their survival.
As global trade surges, so does the underwater noise generated by commercial shipping. From the Arctic to the Great Barrier Reef, scientists have documented how this constant mechanical hum can disorient whales, disrupt migration routes, and drown out the acoustic cues that many marine species rely on to survive.
As the issue intensifies, the United Nations agency responsible for regulating international shipping is now focused on reducing underwater noise.
Arsenio Dominguez, Secretary-General of the UN International Maritime Organization (IMO), has recognized underwater-radiated noise as a critical but emerging concern. "We know the negative impact that shipping has at the bottom of the ocean, even though we're also the main users," he told UN News in Nice during the third UN Ocean Conference (UNOC3), in Nice. "That's why we're taking this very seriously."
New guidelines
More than 80 per cent of global goods are transported by sea. Propellers, hull vibrations, and engines generate low-frequency sounds that travel vast distances underwater. Unlike oil spills or visible trash, noise pollution leaves no trace - but its impact is no less acute.
To address the issue, the IMO has issued new guidelines for the reduction of ship noise and launched a comprehensive Underwater Radiated Noise (URN) Action Plan.
A three-year "experience building phase," during which countries are invited to share lessons and help develop best practices about the new guidelines, is currently underway.
"We now have an action plan to develop mandatory mechanisms learning from this," Mr. Dominguez.
These voluntary guidelines - first adopted in 2014 and updated in 2023 - offer a range of technical recommendations for shipbuilders and operators, including hull design, propeller optimization, and operational measures like speed reduction.
According to the IMO, these changes can significantly reduce noise, especially in "Particularly Sensitive Sea Areas" such as the Galápagos Islands, in Ecuador, and the Tubbataha Reefs, in the Philippines, where marine ecosystems and Indigenous communities are particularly vulnerable.
New technologies and pilot initiatives
The issue of shipborne noise pollution is also gaining traction at UNOC3, as part of its broader discussions on ocean health, marine biodiversity, and the regulation of industrial impacts on the sea. The UN maritime agency is using the gathering to raise the profile of its recently updated guidelines.
Mr. Dominguez pointed to the importance of new technologies in reducing underwater noise: "By enhancing the biofouling and the cleaning of the hulls of the vessels and introducing new technologies, including propellers, we can actually start reducing the negative effects of underwater radiated noise on board the ships."
He added: "Another measure that is effective is speed optimization. By reducing the speeds of the ship, we also reduce underwater radiated noise."
Together with the UN Development Programme ( UNDP ) and the Global Environment Facility (GEF), the IMO has launched an initiative called the GloNoise Partnership, which aims at reducing the acoustic footprint of shipping across in a few pilot countries, including Argentina, Chile, Costa Rica, India, South Africa, and Trinidad and Tobago.
The IMO is on board
"We need to do everything within our power to protect [the ocean]," Mr. Dominguez said. "It's not just the food that we sometimes have on our plates, but it's the goods that are transported by sea. And without them, I don't think the civilizations would actually be able to continue."
The stakes, he warned, go beyond biodiversity.
"This will have a positive impact in relation to the marine conservations in the ocean… Once we gather all this information, we will be able to enhance the quality of shipping when it comes to its efficiency and reduction of underwater radiating noise."
As scientists continue to sound the alarm, Mr. Dominguez said the IMO must move faster: "The big message that I will have from everyone participating in [UNOC3] is let's focus on tangible results. We've made the statements in the past. We have made commitments. It's time to start acting on those commitments and see what has been done and what else needs to be done."
"We are not against this," he concluded. "We are on board."
