SUUNTO D9tx - Manual (Page 64)

5.9.1. Accessing DIVE mode
The Suunto D9tx has four diving modes: AIR mode for diving with standard air only,
MIXED mode for diving with oxygen and/or helium mixtures, FREE mode for freediving,
and GAUGE mode for use as a bottom timer.
The chosen dive mode is displayed when the DIVE mode is accessed, and you can
toggle between the submodes by pressing the UP/DOWN buttons.
5.9.2. DIVE mode activation
Unless the DIVE mode is set OFF, the dive computer activates automatically when
submerged deeper than 0.5 m/1.5 ft. However, it is necessary to activate the DIVE
mode BEFORE diving to check the cylinder pressure, altitude and personal ad-
justment settings, battery condition, oxygen settings, and so on.
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