It looks like Zac Efron and Michelle Rodriguez were setting off their own fireworks over the Fourth of July weekend.

The two actors certainly sparked rumors that they are more than friends when they were caught kissing aboard a friend's yacht on Sunday while vacationing in Sardinia.

Zac can be seen going in for a kiss in a few photos, while Michelle lounged on the boat in a black and white bikini. In other shots, the unexpected couple cuddled in the sun and held hands as Zac helped her on the boat. They shared a sweet moment when Zac affectionately kissed her forehead.

The 26-year-old "Neighbors" star and the 35-year-old "Fast & Furious" actress seemed to be having a great time with their Italian businessman friend Gianluca Vacchi as they swam, tanned and back-flipped off the boat.

Michelle posted an Instagram video on July 4 of herself swimming in a pool with an American flag. A person, whom many are saying is Zac, laughs in the background.

The unlikely duo have been on vacation in Italy together with Gianluca since the end of June. The entrepreneur has posted numerous photos of their fun in the sun, including a shot of him, along with Zac and Michelle hanging out on a dock, and that hilarious video of Zac dancing to Jason Derulo's "Wiggle."

Most recently, Zac was rumored to be dating his "Neighbors" co-star Halston Sage, while Michelle was linked to model Cara Delevingne.

On Monday (July 7) Delevingne posted a Buddah quote on her Instagram, which some fans think may be in response to Michelle and Zac's kiss.