Cardinal Marks flash a white light at night to tell you where there is safe water – keep you away from a danger ie reef, rock, submerged object.

A great way to remember the flash sequence and what cardinal it is, is to think of a clock face.

East is 3 flashes, stay to the east of this marker – safe water lies to the east
. . .      . . .     . . .

West is 9 flashes, stay to the west of this marker – safe water lies to the west
. . . . . . . . .    . . . . . . . . .

South is 6 flashes + 1 long flash, stay to the south of this marker – safe water lies to the south . . . . . . _    . . . . . . _ 

North is continuous flashing, stay to the north of this marker – safe water lies to the north  . . . . . . . . . . . . . . . . . . . .