Jeff Bezos and Lauren Sanchez Partying on David Geffen's Yacht

Jeff Bezos and Lauren Sanchez are living it up with their super elite circle of friends ... floating off the coast of Spain on David Geffen's megayacht!!!

David's looking out for his fellow billionaire ... hosting Jeff and his girlfriend and tons of other big wigs as they live the yacht life in the Balearic Islands off the coast of Spain.

Also onboard David's $400 MILLION floating paradise ... Joshua Kushner and his supermodel wife, Karlie Kloss, oil heir Mikey Hess, former Goldman Sachs CEO Lloyd Blankfein, agent Michael Kives and lawyer Lydia Gray Kives.

David's megayacht, dubbed the Rising Sun, is 454 feet of pure luxury ...the massive ship fits 16 guests and has a crew of 45, and it's got all the amenities you can think of, plus a basketball court!!!

David LOVES hosting super famous people on the Rising Sun -- Bruce Springsteen, Tom Hanks, Oprah, Julia Roberts, Mariah Carey, Leonardo DiCaprio, the list goes on and on -- but it's pretty crazy to see the world's richest man on someone else's boat.