Suunto D4 manual Free diving, Audible and visual alarms

5.5. Free diving

Free diving, and particularly Free diving in combination with scuba diving, may present risks that have not been researched and are not commonly known.

Anyone who engages in any form of breath hold diving is in danger of shallow-water blackout (SWB), that is, the sudden loss of consciousness caused by oxygen starvation. Any breath hold diving results in some nitrogen build-up in the blood and other fast tissues. Due to the short time spent at depth, this build-up is generally not significant. Therefore, provided the effort involved in Free diving has not been severe, there is little risk in diving after breath hold diving. However, the reverse is more unknown and may significantly increase the risk of DCI. Therefore, FREE DIVING AFTER SCUBA DIVING IS NOT RECOMMENDED. You should avoid Free diving, and not exceed 5 m/16 ft, for at least two hours after scuba diving.

WARNING	Suunto also recommends that you receive training in Free diving
	techniques and physiology before conducting breath hold dives.
	No dive computer can replace the need for proper dive training.
	Insufficient or improper training may cause a diver to commit errors
	that may lead to serious injury or death.

5.6. Audible and visual alarms

The dive computer features audible and visual alarms that advise when important limits are approached or that prompt you to acknowledge preset alarms. The table below describes the different alarms and their meanings.

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