Suunto D3 Instruction Manual page 4

Use back-up instruments.
instrumentation including a depth gauge, submersible pressure gauge,
timer or watch, and have access to decompression tables whenever diving
with a bottom timer.
Perform pre-checks. Always activate and check the device before diving
in order to ensure that all Liquid Crystal Display (LCD) segments are
completely displayed, that the device has not run out of battery power,
and that the oxygen, altitude and personal adjustments are correct. Also,
exit the Data Transfer mode before diving, as the computer does not
automatically revert to Dive mode from Data Transfer mode.
Freediving after scuba diving is not recommended. It is recommended to
avoid freediving for at least two hours and not to exceed five meters [16 ft]
after scuba diving depending on your diving activity.
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SuuntoD3.p65 4
WARNING
Make sure that you use back-up
WARNING
WARNING
31.1.2002, 14:16