BALLLLLLLLLLLIN'!!!!!
Magic Johnson has upgraded in a big way ... going from a $500k-per-week yacht to a $700k-per-week yacht -- and he's about to complete his 3RD WEEK on the floating mansion.
The NBA legend is currently floating around the Amalfi Coast with Sam Jackson on a boat called the Siren ... which is advertised at $680k-per-week during Summer high season.
It's 73 meters long -- has a movie theater, gym, dining room, hot tub, helicopter pad, an elevator ... and, of course, WIFI.