Ground-to-air emergency code
These symbols are recognized by Search and Rescue pilots as distress signals. Make sure you make these signals a 6:1 ratio so rescuers can see them from the air.
Aiming reflector
You must carefully aim your mirror’s reflection at the aircraft or vessel you wish to signal, or you may not be seen. You can use a mirror or other reflective items, such as a CD or DVD.
Group splash
If a ring of people all kick simultaneously, the water in the center turns white, briefly, which can be seen against the blue ocean.