The water contact is located on the side of the case. When submerged, the water contact poles are connected by the conductivity of the water. Suunto D4f switches to dive state when water is detected and the depth gauge senses water pressure at 1.2 m (4 ft).
The AC is shown until the water contact deactivates. It is important to keep the water contact area clean. Contamination or dirt can prevent automatic activation/deactivation.
Moisture build-up around the water contact may cause the dive mode to activate. This can happen, for example, when washing your hands or sweating. To save battery power, deactivate the water contact by cleaning it and/or drying it with a soft towel.