Five Chinese students build a low-cost device that lets divers send messages underwater without radio

For most people, sending a message is almost effortless. Underwater, it is a different story. A diver cannot simply pull out a phone and rely on mobile networks or Wi-Fi. Radio-based communication, which works well in the air, is severely limited beneath the surface. That communication gap can become especially serious when visibility is poor or a diver needs to alert someone about a problem.

Five Chinese students have developed a system aimed at addressing exactly that challenge. Called DiveGuard, the project uses acoustic communication to allow short text-level messages to be exchanged between divers and teams at the surface.

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The project was developed by Hao Ting Lyu, Qing Ying Cao, Bai Xuan Ye, Yuanhao Zhang and Jia An Pan as part of the 2026 Conrad Challenge. DiveGuard was selected as a finalist for the 2026 Innovation Summit and later received a Power Pitch Award. The team's official Conrad Challenge profile lists Zhi Heng Dong as its coach.

Why phones and radios struggle underwater

The difficulty starts with the way wireless signals behave in water. Smartphones, Wi-Fi equipment and many conventional radios depend on electromagnetic waves to carry information through the air. Once underwater, however, radio-frequency signals can be absorbed much more readily, making conventional wireless communication difficult.

Divers consequently rely on alternatives. Hand gestures are common. Lights can also be used, while specialised underwater communication equipment is available for situations that demand more sophisticated systems.

But none of those options is perfect. A hand signal is useful only when another diver can see it. Poor visibility can quickly make that method ineffective. Distance can create another problem, and communicating with people on the surface can be particularly difficult.

DiveGuard is designed around the idea that divers need a simple communication channel even when there is no conventional network available.

The students chose sound instead of radio

The key feature of DiveGuard is its use of acoustic communication. Rather than trying to force conventional wireless technology to work underwater, the students' concept converts information into acoustic signals. Those signals can travel through the water and be detected by another DiveGuard device.

The system is intended for short, text-based messages rather than attempting to recreate everything a smartphone can do. That distinction matters. Underwater users may not need internet access or a full mobile phone experience. Sometimes, a brief instruction or warning is enough.

A diver could potentially communicate essential information with another diver or a surface team without depending on cellular coverage or Wi-Fi.

What could divers use it for?

The potential applications are centred on coordination and safety. For recreational divers, a messaging system could make it easier to communicate instructions or changes during an underwater excursion. Professional divers and underwater workers could also benefit when several people have to coordinate tasks beneath the surface.

Then there is the emergency angle. If a diver encounters a dangerous situation, the ability to send even a short message could provide information that cannot easily be conveyed through gestures. This could be particularly valuable when the recipient is a surface team or another diver who cannot maintain visual contact.

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The Conrad Challenge describes DiveGuard as a system intended to support real-time messaging between divers and surface teams and improve situational awareness and emergency response in difficult underwater conditions.

Who created DiveGuard?

The project comes from five students representing China at the 2026 Conrad Challenge. The team comprises:

• Hao Ting Lyu
• Qing Ying Cao
• Bai Xuan Ye
• Yuanhao Zhang
• Jia An Pan

DiveGuard, identified as DG-01, competed in the Cyber-Technology & Security category. Its selection as a finalist took the project to the 2026 Innovation Summit, where student teams presented ideas addressing challenges in fields ranging from technology and aerospace to health, energy and water. DiveGuard subsequently received a Power Pitch Award at the summit.

Could cheaper technology open up underwater communication?

One of the central ideas behind the project is affordability. Sophisticated underwater communication systems already exist, but specialist equipment can be expensive. That can make advanced communication technology less accessible to recreational divers, smaller operators and organisations working without extensive underwater infrastructure.

DiveGuard is being positioned as a lower-cost alternative aimed at providing a more basic but potentially useful messaging capability.

The team has identified recreational diving as part of its broader market opportunity. Its Conrad Challenge profile also points to smart diving devices and the wider dive tourism industry, with an initial focus proposed on Southeast Asia.

That region has a substantial connection to recreational diving and marine activities, making affordability an important consideration for any technology aimed at expanding access.

Why sound is a natural choice underwater

There is nothing particularly unusual about using sound beneath the surface. In fact, acoustic technology is already fundamental to many underwater applications. Sonar, navigation systems and various forms of underwater communication all take advantage of the fact that sound can travel efficiently through water.

DiveGuard applies that basic principle to a much simpler objective: exchanging short messages. The engineering challenge is making such a system small, affordable and dependable enough for practical use.

The decision to concentrate on short messages could help. A device does not necessarily need to provide the full functionality of a smartphone if its main purpose is to transmit critical information. An instruction, warning or emergency alert may be all a diver needs to send.

What happens next for DiveGuard?

DiveGuard remains a student innovation, not a proven replacement for professional underwater communication equipment. Its recognition at the Conrad Challenge nevertheless highlights the attempt to address a genuine problem using a relatively accessible technological approach.

The question behind the project is simple: how can people communicate when conventional wireless networks stop working because they are underwater? The students' answer is to replace radio with sound and keep the communication focused on short messages.

Whether that idea eventually becomes a commercial product will depend on how reliably and affordably the concept can be developed. But if the technology can make that transition, it could offer divers a useful capability that is often taken for granted on land, the ability to send a message when something goes wrong.