small, cheap pressure sensor with high precision for under water use


there are a lot of pressure sensors out there and I have been searching for quite some time now, but I haven't found the right one yet.

What do I need:
I need a small pressure sensor (2 by 2 cm max) that is or can be made water-proof. Also it should be relatively cheap (1 to 10$ max). What I have found so far:

(Can't see how big, and if or if not water-proof)

This one is good and I am using it, but the precision is not too good.
And all the other ones from Tekscan are pretty good as well.

Could somebody tell me something about pressure sensors and what kinds there are and what would be good for me?

Also precision plays a big role.

The MS5837 fulfils your size requirement (it's 3.3 x 3.3 x 2.75mm), your precision requirement (very high: 24-bit) and it's designed for underwater use. It's predecessor (not rated for underwater use) reportedly can work for over a year under water.

I have some of them - will start testing soon. Hope it works as advertised, as they're expensive at almost USD 20 each, so may not fulfil your price requirement (you didn't state which $).