The 28-year-old actor and Kelly, 26 were filming scenes on a boat alongside their co-star Alexandra Daddario.
Kelly was dressed in a glamorous look from the waist up, most likely shooting close-ups. Alexandra was spotted sitting alone on the doc while checking her phone between takes.
Two nights earlier, Zac had been spotted out hanging out with some friends at one of the local bars in town.
10+ pictures inside of Zac Efron and the Baywatch cast filming night scenes…