Depth sensor

Hi to this amazing community . I'm a Newbie who has the following project in mind . I thought it was easier, but I have no idea how to carry on . I'm a diver who wants to make a profundimeter to measure how deep I am . As I didn't find any depth sensor, I thought in using a pressure sensor. I had some ideas , like using a barometric sensor inside a sealed cilinder to measure the pressure of the air inside it, but then I realised that, if I put surface air, I will have always the same pressure . Sorry if it sounds silly . So I have no ideas .

I don't see how to solve it . If anyone could help me, I would thank it. Thanks in advance .

I'm guessing the cylinder wouldn't work as it's a rigid object, therefore not changing a lot according to the outside pressure. But maybe if the sensor is inside a rubber ball, for example, I'm guessing (although I don't have diving experience), that this way the outside pressure will infer on the pressure inside, therefore allowing to measure the change in pressure.

Just a thought... :)

Great idea . When you dive , as you go deeper, the preasures increases one Atm. each ten meters . If I put the sensor inside a rubber ball, it may work . I’ll give a try and comment the results . Byeee.

you could take a balloon in a cylinder(open at both ends). The cylinder protects the balloon and the electronics?

My idea is , as it is an original prototype , use a tupper Ware or something similar to the electronics , and put the barometer inside the balloon .The tupper and the ballon ( or the cilinder ) will be fastened , and electronics and balloon will be joined via wire. If the balloon crashes, the only components I would break is the barometer . I Will have to seal the tupper in a strong way .

You can get differential pressure sensors that have one end sealed at atmospheric pressure and the other end open. You can get versions that can stand liquids in the open end. Salt water is on of the liquids that can be used.

Thanks to everyone . I think I have found the solution here :