This article was originally shared by the UN Decade on Ocean Science.

This article is part of our new ‘Ocean Science in Action’ series, which highlights achievements and success stories from our network of endorsed Decade Actions.

As fast as a commercial jet and capable of crossing an entire ocean in less than a day, tsunamis are among the most devastating natural hazards. Across the world, millions of people living in coastal communities are vulnerable to tsunamis.

In this article, we highlight three initiatives endorsed by the UN Decade of Ocean Science for Sustainable Development 2021-2030 (‘Ocean Decade’) that are pioneering innovative solutions to better understand tsunamis, prepare coastal communities, and raise the alarm when waves occur.

“Everyone turned and looked towards the sea. I saw it too. The water came as high as a cloud. At first I didn’t think it was water,” recalls Arjunan Anjappan, a survivor of the Indian Ocean tsunami that happened in 2004. It was one of the deadliest disasters in recent history, claiming around 230,000 lives across 15 countries.

Tsunamis are one of nature’s most powerful forces. In deep water, their waves can stretch over 100 kilometers and travel at speeds of up to 800 km/h, yet rise only a few centimeters on the surface, invisible to ships at sea. But as they near the coast, the waves slow and tower into walls of water that can reach 30 meters high or more.

The Pacific is the most active tsunami zone, located around the geologically active “Ring of Fire”. But they also occur in other parts of the world, including the Caribbean sea, the North -Eastern Atlantic Ocean, the Mediterranean sea, and the Indian Ocean. The Caribbean alone has seen more than 75 tsunamis in the past 500 years and can expect around four destructive tsunamis per century in the future.

As part of the Ocean Decade, scientists around the world combine tech innovation with natural resilience, from self-raising sea barriers and tsunami sensors to restoring mangroves and reefs. The three success stories below highlight how the Ocean Decade is turning hard-won lessons into science-based solutions for coastal preparedness and resilience.

The Ocean Decade Tsunami Programme: Global cooperation for tsunami risk mitigation and early warning systems

The 2004 Indian Ocean tsunami was a global wake-up call. Since then, the Intergovernmental Oceanographic Commission (IOC) of UNESCO has led international efforts to reduce tsunami risk worldwide.

Recent tsunami alerts have shown the value of this global cooperation. When a strong earthquake struck off eastern Russia last summer on 29 July 2025, sirens sounded across Pacific coasts, and waves reached Japan more than a thousand kilometers away within an hour. Following decades of cooperation under the IOC, millions of people were alerted within minutes, enabling immediate protective actions and helping prevent loss of life.

The IOC’s Ocean Decade Tsunami Programme aims to ensure that tsunami warning systems can issue actionable alerts within ten minutes, reaching all coasts at risk. Hosting 13 Decade Projects to date, the Programme is strengthening early warning capacities across the Pacific, Indian Ocean, the Caribbean, as well as North-Eastern Atlantic, the Mediterranean, and Connected Sea regions.

The Programme has also now supported more than 100 communities in 43 countries to be “Tsunami Ready” – the IOC standard to assess a community’s preparedness for tsunamis. Among them, 15 communities are in Small Island Developing States, those most vulnerable to the ocean’s power but leading the way in tsunami response. Indicators of preparedness include the mapping of tsunami risks, installation of public signages, development of a response plan, and regular tsunami evacuation exercises.

“Our progress toward achieving the Programme’s ambitious 2030 goal of ensuring that coastal communities are “Tsunami-Ready” will only be possible through strong and sustained international cooperation, strategic investment, robust partnerships, and effective coordination,” said Denis Chang Seng, IOC Programme Specialist, CoastWAVE Project.

Dr T.M. Balakrishnan Nair, Director of the Indian National Centre for Ocean Information Services (INCOIS), highlighted the importance of India’s efforts to advance “Tsunami Ready” goals: “India’s Tsunami Ready achievements, aligned with the Ocean Decade Tsunami Programme’s 2030 goal of making every coastal community Tsunami Ready, reflect the nation’s vision of combining ocean science, community action, and self-reliance under Atmanirbhar Bharat to build a safer and more resilient Indian Ocean region.”

Tsunami & Climatic Risk Reduction at Protected Areas: Building resilience along Costa Rica’s shores

Rainforests, volcanic peaks, and turquoise shores – over 25% of Costa Rican territory consists of Wildlife Protected Areas, and nature tourism is one of the main economic activities of the country. Yet Costa Rica’s natural treasures are also vulnerable: since 1746, the country has faced over 45 tsunamis along both its Pacific and Caribbean coasts.

Led by the Program SINAMOT at the National University, the Decade Project Tsunami & Climatic Risk Reduction at Protected Areas focuses on enhancing the preparedness of Wildlife Protected Areas and their surrounding communities for tsunamis and climatic risks such as flooding.

“Conservation efforts and policies have become part of Costa Rica’s identity, and coastal communities near National Parks are strongly involved, either in touristic businesses or NGOs,” explained Dr.rer.nat. Silvia Chacón Barrantes, Head of SINAMOT. “Therefore, tsunami preparedness efforts are articulated between SINAMOT, the National Emergency Commission, the National Parks and the neighboring communities, to increase their effectiveness.”

The initiative develops tsunami inundation and evacuation maps, preparedness and action plans to reduce both climatic and psychosocial vulnerabilities. It also supports national and international recognition of its coasts, helping local communities achieve “Tsunami Ready” status. Two communities covering national parks have now been recognized under the IOC tsunami preparedness standards, and several more are close to achieving the required guidelines.

SMART Subsea Cables: Reimagining telecommunications to protect the ocean and our lives

Every time you send an email or stream a video, cables beneath the ocean connect our world. These same cables now hold the potential to connect humanity to the Earth itself.

The SMART (Science Monitoring And Reliable Telecommunications) Decade Project is transforming global telecommunications into a dual-purpose infrastructure serving both connectivity and science for the benefit of society. By integrating high-precision sensors into future undersea cables, SMART enables the continuous monitoring of ocean temperature, pressure, and seismic motion along the seafloor, providing essential data to understand and respond to climate change, sea level rise, ocean heat content, and natural hazards such as earthquakes and tsunamis.

SMART is an Emerging Network within the Global Ocean Observing System (GOOS) – coordinated by the IOC – filling one of the greatest gaps in ocean observation: the absence of continuous, high-resolution, long-term (25 years) data from the deep ocean. This unique data stream can only be achieved through collaboration between the telecom industry, scientists, and governments, ensuring that future connectivity infrastructure also serves the planet.

Co-sponsored by the International Telecommunication Union, World Meteorological Organization, and IOC, SMART exemplifies how international cooperation can turn vision into public good. The technology is now commercially available, marking a turning point where transoceanic, regional, and island-scale cable systems can observe the ocean and earth while connecting people.

Governments, scientists, and industry leaders from Portugal, France, Vanuatu, Chile, Italy, and many more countries are joining forces to launch this new generation of cables. As of October 2025, the first two SMART systems are now underway:

• The Atlantic CAM System, linking Continental Portugal, Madeira, and Azores, the world’s first fully funded SMART Cable System;
• The Tamtam System, connecting Vanuatu and New Caledonia, the first Pacific deployment advancing climate and disaster resilience goals in the Small Island Developing States.

At the same time, feasibility studies are advancing Antarctic SMART Cable systems, extending the reach to one of the most remote and fragile polar regions.

“SMART Cables embody the spirit of international cooperation, linking nations, science, and the subsea telecom industry beneath the sea to deliver continuous, open, and high quality data from the deep ocean,” said Ceci Rodríguez Cruz, Director of the SMART Cables International Programme Office at the University of Hawai’i at Mānoa. “Together, we are shaping the digital and scientific foundations that will define resilience for generations to come.”

Tsunamis know no borders. These initiatives demonstrate that effective coastal resilience is built where international cooperation, local leadership and engagement, and high-tech innovation come together. Through the Ocean Decade, science is not only helping us understand the ocean, it is helping us live safely alongside it.

For more information, please contact:
Ocean Decade Communications Team ([email protected])

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About the Ocean Decade:

Proclaimed in 2017 by the United Nations General Assembly, the UN Decade of Ocean Science for Sustainable Development (2021-2030) (‘the Ocean Decade’) seeks to stimulate ocean science and knowledge generation to reverse the decline of the state of the ocean system and catalyse new opportunities for sustainable development of this massive marine ecosystem. The vision of the Ocean Decade is ‘the science we need for the ocean we want’. The Ocean Decade provides a convening framework for scientists and stakeholders from diverse sectors to develop the scientific knowledge and the partnerships needed to accelerate and harness advances in ocean science to achieve a better understanding of the ocean system, and deliver science-based solutions to achieve the 2030 Agenda. The UN General Assembly mandated the Intergovernmental Oceanographic Commission (IOC) of UNESCO to coordinate the preparations and implementation of the Decade.

About the IOC:

The Intergovernmental Oceanographic Commission (IOC) of UNESCO promotes international cooperation in marine sciences to improve management of the ocean, coasts and marine resources. The IOC enables its 152 Member States to work together by coordinating programmes in capacity development, ocean observations and services, ocean science and tsunami warning. The work of the IOC contributes to the mission of UNESCO to promote the advancement of science and its applications to develop knowledge and capacity, key to economic and social progress, the basis of peace and sustainable development.