The giant (5 m high) purple cow is back at Hamburg... #MUHBOOT making a trip on the Elbe, seen from Bubendey Ufer, Hamburg, 31.07.2015

Some data according to Wikimedia Commons...

Built by Boot shipyard, Alpen a/d Rijn, the Netherlands
Year of build: 1930

L/B/D (M): 40,00* / 4,65 / 1,32
*(30 m as built)

First name: Catharina Cornelia
1999 renamed Veruna
2014 (?) renamed #muhboot

http://www.milka.de/ (because of the brand logo in the photo)