It is easy to assume that you would never need to clean a dive computer given that they spend most of their life underwater. Yet, it is quite amazing to think of the inhumane amount of ways that a technology device can get dirty and dive computers are certainly no exception. One of the most important things you need to avoid is to allow salt to build up anywhere on your computer. This could almost be considered a disease to dive computers and when they do succumb to salt, thoroughly wash them with fresh water. But, make sure to avoid using cleaning chemicals or detergents as this can damage the computer.
Also, avoid high-pressure washing as this can damage the depth sensor. Finally, you could also choose to clean the metal contacts with a soft brush and fresh water.