When I saw this mega-yacht, I thought that it had to be a British yach, because of the Union Jack like flag. With the awesome power of google I found that, in fact, this is a Microsoft sighting.
"Scat", the first yacht for Charles Simonyi, a driving force behind the development of Microsoft Excel. You could easily mistake her for a military vessel, given the large “9906” that’s painted on her hull in block lettering and the grey paint scheme. The numeric code was her project number while she was under construction, and the paint color was chosen because it’s easier on the eyes than “wedding cake” white. ("Power and Motor Yacht: World's 100 Largest Yachts")