My grandfather just passed and I was lucky enough to receive this medal. He was a WWII Veteran that served in the 9th Armored Division; he drove a tank.
The front says "SEEFAHRT 1ST NOT" across the top. "TAG DER DEUTSCFHEN" on the left hand side. "SEEFAHRT 25.26.5.1935" on the right hand side. "HOFFSTATTER BONN" on the back.
Any direction or background would be helpful.
According to a lot of websites, its a merchant service badge; I've been looking for a better description, but that's about all I could find. Sorry.
http://collections.rmg.co.uk/collections/objects/39923.html
Its interesting because the badge is seemingly connected to naval service or at least some sort of nautical accomplishment; I'd be interested to know the story behind this badge. I'm sorry for your loss, by the way.
"Seefahrt ist Not" seems to be the title of a book by German author Gorch Fock and it was successful and influential. Your pin makes reference to a "Day of German Seafaring 15-16.5.1935" On the back it seems to be a name and city, presumably of the bearer. I conclude this from seeing other versions of this pin with other names/cities on the back.
I found some more info about that day here. It says that the day was a celebration of German seafaring held by the foreign department of the NSDAP, Goebbels even held a speech in Hamburg and visited a Wohnschiff [living ship] crew of the Kriegsmarine the next day, on which Rudelf Heß also held a speech.
I could not find anything on how and to whom it was given, though.