In a way, our options are pretty limited when it comes to finding our way around the ocean. While GPS is fine if you're skipping over the surface of the water, it becomes useless at depths of just a foot (30 cm). Scientists are claiming a new breakthrough in the world of underwater navigation, taking inspiration from marine animals that use polarizing light in some clever ways.

"We studied marine animals as we believe some species could be using the polarization of light to navigate, and our new study is a proof of concept that this is possible," says Dr Samuel Powell, research fellow at Australia's University of Queensland and member of the research team.

While marine animals like squid, shrimp, cuttlefish and octopus were already known to use polarized light to communicate, us humans are unable to pick it up without using specialized lenses, like those used in polarized sunglasses. These creatures can not only detect it, but reflect it to reveal their presence to aggressive competitors.

So Powell and his colleagues suspected that the creatures could also use the light to navigate, and built an imaging system equipped with polarization sensors to explore the possibilities. These sensors rely on the light's transmission and scattering through the water, and use these patterns to work out the sun's position in the sky. In turn, this makes the system able to be used as a compass and for geolocalization purposes.

"Currently, submarines use GPS systems at the surface, and when they descend they rely on dead reckoning to calculate their position," says Powell. "The error in this case is unbounded – that is, the longer without GPS, the more erroneous your calculation can be."

The team tested the new system at different underwater locations around the world, at varying depths and times of day. The researchers say the early data suggests the margin for error for its geolocalization system to be six meters (20 ft) for every kilometer (0.62 mi) traveled. While still in its proof of concept stage, the researchers believe with further development the technique could enable navigation at depths of up to 200 m (656 ft) for sustained periods of time.

"Using polarization sensors, our method would allow for real-time geolocalization underwater with more accurate long-distance results, without the need to resurface periodically," says Powell.

The research was published in the journal Science Advances.

Source: University of Queensland