Mark Zuckerberg's MegaYacht 'Launchpad' Sets Sail in San Diego Bay, on Video

Mark Zuckerberg's trading a Silicon Valley office for some time in the big, blue sea ... with his 387-foot yacht leaving the harbor for the wide-open ocean.

The tech mogul's megayacht left San Diego Harbor Sunday afternoon ... gliding away from the shore and navigating its way to the mouth of the bay.

The ship's moving pretty quickly in the clip, as its hulking hull carefully maneuvers past much smaller vessels. It eventually makes it out to sea ... an impressive sight.

Worth noting, we don't actually see Zuck in the clip ... so, unclear if he's onboard or if the ship's meeting him somewhere. Zuckerberg reportedly paid approximately $300 million for the ship, which can reportedly travel at up to 27 miles per hour.

The ship -- named "Launchpad" -- also has a support vessel, "Wingman" ... a 220-foot ship outfitted with the capabilities to accompany the ship on its journey.

BTW ... Zuck recently had a security issue with "Wingman" -- when a man allegedly snuck aboard the yacht last week and was arrested by police without incident.

Hopefully, Mark's telling "Launchpad" where to go ... and, it wasn't taken by an opportunistic trespasser!