Preventing Marine Disasters - BOSAI: Science that Can Save Your Life

Japan is surrounded by the sea. Japanese people have a deep connection with the sea and beaches are popular in summer. The blue seas and white sandy beaches are a refreshing sight. Delicious food is also on hand at the seasonal beach huts. However, even a momentary lapse in concentration can be dangerous around the ocean. In 2024, 830 people were involved in ocean-related accidents. 212 of those were deaths or missing persons. Efforts are underway to address ocean dangers using new digital technology. An accident prevention system that instantly detects and alerts users to dangerous rip currents using AI-based image analysis. A marine rescue system that connects smart devices to satellite communication and shares the location of multiple people via an app. Today, we will see how digital technology is being used to prevent water accidents and aid rescues. BOSCI, science that can save your life. We're here at Yuigahama Beach in Kamakura City, Kanagawa Prefecture. This seashore is easy to reach from the city center. That makes it a popular spot in summer, attracting not only locals but also tourists from overseas. We spoke to some visitors about Japanese beaches. Where are you from? I'm from India. What do you like about beaches in Japan? The beaches are clean and we can enjoy in water. It's very peaceful. Where are you from? I'm from Moscow, from Russia. What do you like about the beaches in Japan? It's very sunny, it's hot, but with the wind, it's very pleasant to just relax on the beach. Where are you from? I'm from Italy. So what do you like about the beaches in Japan? I like the natural part of the beaches in Japan. So I'm from Italy where all the beaches are very developed. We have a lot of umbrellas and beds. Many tourists enjoy the beach in Japan. At a beautiful beach, it's easy to feel relaxed. Yet one must not forget that the sea also has risks. In June 2025, a tragic accident at this beach saw two men swept out to sea. One was rescued but the other lost his life. Every year, there are accidents at sea that result in casualties. Why do these occur? Dr Toshinori Ishikawa has long been studying ways to reduce water accidents while promoting use of the sea. Dangers around the water abound, such as being blown out to sea by wind or suddenly losing your footing and drowning in deep water. But the greatest danger at the beach is rip currents. Waves roll in from the open sea toward the shore. And when they break, currents are created that flow not only toward the shore, but also away from it. These are called rip currents. Rip currents can occur on any coastline. And since they are difficult to recognize with the naked eye, accidents where people are unknowingly swept out to sea continue to occur. This is an experiment to visualize a rip current. Environmentally safe green dye is released into the sea and its spread is observed. The dye moves toward the open sea in a straight line. Two minutes after starting the experiment, the dye travelled some 50 metres offshore. Together with Ishikawa, I observed a rip current which is difficult to detect when it occurs. A rip current is occurring somewhere in this video. Can you spot it? Actually, according to Ishikawa, the rip current is occurring here. The rip current is occurring here. Can you spot it? How can rip currents be detected? We use the function of augmented reality to transfer the position of the rip current to the smartphone camera. At the core of the system is AI image analysis technology. While AI excels at image analysis, it struggles to identify moving objects like water. Ishikawa requested the cooperation of three lifeguards with over 15 years of experience who can identify the occurrence of rip currents. Based on characteristics such as fewer white waves and a darker sea surface colour compared to the surrounding area, about 50,000 still images were created from videos of rip currents at Yuigahama Beach and these were used to train the AI. He also prepared still photos of the ocean without rip currents as a comparison and repeatedly trained the AI with them. After six years of continuous learning, the AI could detect rip currents in real time with approximately 80% accuracy. This system has been in use at this beach since 2022. Six cameras continuously record the coastline. Sending three to four images per second to a university server where the AI analyses the images in real time. When the AI detects a rip current, a notification will be sent to a beachgoer's smartphone app. And with AR, the location of the rip current can even be displayed on the smartphone's screen. In addition, if someone is swept into the rip current area, a rescue request will be sent to the lifeguard's smartwatch enabling them to quickly respond to the emergency. Anyone can use the AR function by scanning the QR code and downloading the app. Besides rip currents, the system displays hazardous areas such as rocky places along the coast as well as evacuation routes during a tsunami so it can address various marine risks. AI-based rip current detection systems are currently being used at six beaches nationwide. At a beach in Fukui Prefecture, this system has even been combined with drones. When the AI detects people in the rip current area, the drone automatically flies to the location of the person swept away and alerts them to the danger, enabling swift rescue. But even then, some risks can still remain. That's why technology is now being developed to save lives in the event that someone does get swept out to sea. Let's go take a look. Iwanaga Chika is developing technology to search for people in distress at sea by integrating her 25 years of scuba diving experience in oceans around the world into an app. What's the biggest difference between this technology and the technology we've seen so far? Satellite communication is now directly connected to the device, so the biggest feature of this technology is that you can use that communication to let the other person know where you are. Diving computers with GPS functionality receive signals from GPS satellites and can confirm your location. However, in order to notify others of your location, a separate transmission function was required. Therefore, if you were stranded at sea and didn't have that function, you would not be able to do that. So Iwanaga is developing an app that allows users to share their location information even in remote places such as at sea. The app utilizes commonly used smart devices. If a person in distress cannot send their location information received from a GPS signal via a land-based internet connection, they can send it to an internet server via a communications satellite. Rescuers can then access this server to obtain the person's location information. Vital signs data is also shared, allowing rescuers to determine the condition of a stranded person in advance. And collaboration with medical teams enables more precise rescue operations. The system that Iwanaga is planning to utilize, which employs communication satellites, is still under development. So I tested out the app's functions using a land-based internet connection. Iwanaga is using a smartphone. I am using a smartwatch. The two devices are connected via the app. My location information is sent to the smartphone and an icon is displayed. I start walking off to simulate being swept away. We've already walked quite a bit. I feel like it has to be at least 100 meters or more. 200? Checking the smartphone to see how far I've gone indicates that I've traveled 181 meters. Iwanaga believes that this system would allow people in distress in the ocean to send their constantly changing location to rescuers, enabling faster rescue operations. This experiment was conducted along the shore, but previous experiments have confirmed that location information can be shared even at sea. Research is also underway to find the location of divers. This involves underwater users sending light signals from a device toward a camera installed on the water surface, with a camera identifying the underwater user's ID and location. Researchers could determine the user's ID and location when optical signals were sent toward the camera from a depth of 15 meters. Research is now underway to enable an app to identify the user's location, whether on the surface of the water or underwater. Thanks to advancements in AI and communication technology, disaster countermeasures for marine recreation are developing day by day. If you go to the beach, enjoy the beauty of the ocean, but also remain mindful of nature and prepare for the risks it poses.