Mark Zuckerberg's summer of Man vs. Wild 2019 is in full swing up in Lake Tahoe -- where he's now a boating captain ... with a little assistance from the crew, of course.
The Facebook founder and CEO was at one of his two new Tahoe waterfront estates Saturday -- properties he reportedly dropped around $60 mil for this past winter -- and Zuck was getting briefed on a new operating system ... it's called HowToSteerVessels 2.0™.
Eyewitnesses tell us Mark and some pals were being taught how to steer this boat, and that he even got behind the wheel at one point as it drifted away from the dock.