Freediving goggles work by "leaking" under pressure
Freedivers – those people who dive to great depths without an air supply – typically have to use masks instead of less bulky, more hydrodynamic goggles. A group of Italian entrepreneurs have set out to change that, however, by designing goggles that take on water as they go deeper.
The problem with using regular swimming goggles for freediving is that the air held within them compresses at depth. This creates a vacuum inside the goggles which sucks on the diver's eyes, causing blood vessels in them to rupture. By contrast, because the diver's nose is included inside of a mask, they can simply blow air out of their nose and into that mask in order to equalize pressure.
That's where Hektometer goggles come in. They're different from regular goggles in that they have a flexible silicone membrane inside of them, along with small holes that allow water to enter from the sides.
As the diver descends and the surrounding water pressure increases, water enters the goggles, compressing the membranes in toward the middle. This means that there is progressively less and less of an airspace within the goggles, the deeper the diver goes. That keeps a vacuum from forming, saving the diver's eyes.
When they ascend, the airspace expands again, forcing the water back out.
Along with being more streamlined than a mask, Hektometer goggles also allow the diver to wear a nose clip. This is an important consideration, as it means that they can equalize their ear pressure hands-free – when wearing a mask, they can't also wear a nose clip, so they have to reach forward and pinch their nose closed with their fingers while equalizing.
Additionally, because the diver doesn't need to blow out through their nose to equalize the pressure inside a mask, more air can remain stored in their lungs.
If you're interested in getting a pair of Hektometers – which are also said to be good for activities such as spearfishing – they're currently the subject of an Indiegogo campaign. A pledge of €149 (about US$183) is required, with the estimated retail price sitting at €180 ($221). Assuming they reach production, delivery is planned for next month.