SUUNTO SK-8 DIVE COMPASS NH - Manual (Page 4)

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Do not use the compass before you come to rest and can align the
compass horizontally with the aid of a flat bottom, a glimpse of the
surface, your own bubbles going up, or the pull of gravity. In poor
light or very murky water, swing the compass slowly from right to
left to ensure the compass card moves freely before checking your
bearing.
NAVIGATION AIDS UNDER WATER
The dip and stratification of rocks on the shore can often be followed
over large areas under water. Sand ripples may also form long lines
parallel to the shore that can be used for maintaining your direction
of travel.
The direction of currents should be noted by their effect on algae
or drifting particles. Use the compass to check the bearing of the
current.
Swimming in a straight line along the bottom is greatly facilitated if
you can line up three distinctive targets in your line of vision. As you
reach the first target, line up a new one farther away, so that you
again have three points determining your course. This way you can
counteract the effect of a side current.
In clear water, the compass can be used to swim in a search pattern
over a fairly large area. Count your swim kick pairs (each left or each
right kick), swimming on one of the cardinal directions (North, South,
East, West).
Count up to 100 kick pairs (roughly 100 meters), turn 90 degrees,
swim a few kicks, then turn 90 degrees further, and again swim
the same number of kick pairs. Continue the pattern for as long as
necessary.
The side displacement between each turn in a search pattern depends
on visibility. Keep the disatnce between each turn shorter than
theoretically possible.