Ariadna: 3D Mapping Underwater for Divers

The Finnish team of Project Ariadna claims it will soon offer an affordable device that indicates the position of divers while underwater. One look at the wrist display informs the diver about his depth, the distance covered, the route that was taken and the way back to the boat where the dive started.

No satellites

Underwater navigation is a newly developed technology. The signals of navigation satellites do not reach more than 2 millimetre underwater. Calculating the exact position of the diver is therefore achieved by combining data from all the different instruments a scuba diver uses. The result is a 3D projection of the underwater route and a heading to any point of interest or the boat. Project Ariadna will launch a limited prototype version this year and is planning to launch a first production series of underwater navigation sets in 2017.

Distance and direction

“Underwater navigation has been researched for a long time,” lead electronics engineer Pasi Lathinen affirms. “We have created a simple tool that brings information about their position to every diver’s wrist. Distance covered and direction in which the diver has swam are calculated to determine his position.

Our sensor is attached to the diver’s ankle. This sensor measures the movement of the leg and thus knows the amount of forward thrust the diver generates with his flippers. This information is combined with underwater drag and possible current. For accurate positioning, the device should be calibrated. Exact drag from the diver’s body and diving equipment can then be calculated.

However, the self-learning feature is so powerful that even without calibrating, the underwater navigation will prove quite accurate: Ariadna’s navigation can locate the diver within 20 metres after an hour of moving about.

Just before diving under and just after resurfacing, the sensor reads GPS satellites to match the measured under water movements. Just like the track the diver swam, these satellite fixes are stored.”

Complex programming

While Ariadna’s project team composed of five people has now been working for almost six years on the underwater navigation device, Lathinen describes the instrument as ‘simple’.  “We use instruments and sensors that are readily available on the market. These get more accurate and even cheaper all the time.

project_ariadna_photo_3The essence of our project is the software. This has zero marginal cost. We only need to earn back the time invested to develop this software. This is why I believe we can provide a good navigation system at a price any diver would be willing to spend. This will be in the range of a few hundred euros to maximum one thousand”

Underwater signal

Doing justice to the team, one needs to acknowledge one big innovation. Says Lahtinen: “The most important innovation we developed is the wireless data signal that works well underwater. This is a double frequency radio signal, different from conventional radio signals or ultrasound. The problem with these other signals is that you get a lot of bias on the signal underwater. By having the compass, depth meter, watch and our sensor communicating simultaneously, a reliable positioning is possible.”


Reliable positioning and underwater navigation is expected to make diving safer. Additionally, information about remaining air pressure is displayed. Divers can share points of interest, so anyone within the group may be directed to a wreck, a cave or an anchor while underwater.


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