John Weiss wrote:

Personally, I have yet to encounter a situation in my kayak where I needed
anything more than a whistle, though I have considered adding a signal
mirror
to attract the attention of landing seaplane pilots.


John,
With the perspective of a former airplane pilot, I will urge you to
be very careful if you choose to use a mirror to reflect the sun into
the eyes of a landing seaplane pilot. It is hard enough to see clearly
through a spinning propellor and have good judgement from altitude above
water *compared to* what you may be able to see (it is a different
perspective- you may be invisible to him in a glare or blend into the
background, etc). Things happen relatively quickly in an airplane when
something goes wrong at low altitudes, so blinding a pilot on his final
approach to landing is a prescription for getting not only yourself
killed if you are in his path, but almost assuredly also his passengers
and crew. Instead you should make sure you are that much more visible to
him so he can't miss seeing you.
Red