Lauren hopped in her billionaire fiancé's helicopter Wednesday off the coast of Sardinia, taking the controls and zipping around before successfully landing on the support yacht for the Amazon founder's superyacht.

Yes, Jeff's new $500 million superyacht, Koru, also has a $100 million support vessel ... it's named Abeona, the Roman goddess of voyages and departures, and it's got a helipad.

It looks like Lauren was practicing takeoff and landings, because she went up and down a few times.

Our sources say Lauren pilots this helicopter often, usually to airports where the couple hops on private jets, and this wasn't her first time landing on Abeona.

Lauren's parents are both pilots and she got her helicopter pilot's license from a flight school in Los Angeles ... she also had her own aviation company and now she's landing choppers on yachts parked off Italian islands.

Before Wednesday's takeoff and landing, we saw Lauren and Jeff returning from land on a souped-up speedboat as they continue their early honeymoon across Europe.