On a nice sunny day, this umbrella may look no different from any other, but once it gets wet, the hydrochromatic inks come to life. Unfortunately, Squid London only put out a limited number of these umbrellas, all of which have been claimed. Click here for one more picture.
According to Wikipedia, hydrochromatic ink was originally developed by a subsidiary of the Pilot Pen Company in Japan, and is probably most easily recognizable as the ‘secret’ behind the Aquadoodle childrens toy.
[via OhGizmo]