In case there's a bear that comes at you like The Revenant this summer on the family camping trip. Oh wait, that's just a three-year old throwing a tantrum.
So in case you don't know the code for SOS, let's travel briefly back to the 1950s. This is the Morse code for SOS:
Three, THREE, three.
There seem to be no good mnemonics available, so memorizing three, THREE, three seems like the best way to go.
(There's an app for everything, but maybe knowing what it is would be helpful if the phone dies?)
It is basically three short taps, three long taps, followed by three more short taps. To repeat it, somebody would start again with the short taps (so, essentially, six short taps in a row).
This can be repeated with any light or sound mechanism, though shooting off a flare seems just as extremely effective when you've been adrift at sea for 41 days.