The former The Vampire Diaries star, 26, wore a pink bikini as she smooched the Whiplash actor aboard a yacht off the coast of the French Riviera.
The pair gleefully slid down the boat's inflatable waterslide and also hopped aboard a jet-ski. Stowell, who donned black swim trunks with yellow smiley faces, manned the vehicle as Dobrev clung to his waist.
Dobrev also wore a striped one-piece suit while frolicking in the sun.
Kat Graham Sounds off on The Vampire Diaries Finale
The couple has been spending quite a bit of time together including a June date at the Hallmark Shoebox relaunch in Hollywood. An onlooker told PEOPLE that the couple spent the evening "getting cozy" and laughing together at the comedy show.
The actress even brought Stowell along to watch her movie The Final Girls at the Los Angeles Film Festival gala last week.