Water depth is easily determined by measuring the water's pressure. As a first approximation, pressure increase of 1 bar for every 10 meters of depth. Diving computer using the MS5535 or MS5541 can accurately measure depth down to 130 meters (since the MS5535 is a 14bar sensor).

The MS5535 or MS5541 have a typical resolution of 1.2 mbar representing a water height of 1.2 cm.
Thanks to their digital interface, they can be directly connected to any microcontroller. The internally stored compensation coefficients, increase dramatically the resolution of the device, thus allowing high-precision appliances.

The MS5535 can be ordered with or without protecting gel. This gel will insulate the sensitive part of the sensor from external environment. For more details, follow these links: MS5535/MS5541.