Zac Efron posts shirtless photos of abs with brother Dylan

The Efron genes run strong.

Zac Efron sent hearts racing after posing a series of shirtless snaps alongside his younger brother, Dylan Efron, to Instagram Friday.

The hunky siblings looked ripped as they posed in their swim trunks after enjoying a day of boating in Coeur D’Alene, Idaho.

While Zac, who wore palm tree and crystal pendant necklaces, showed off his chiseled abs in navy patterned shorts, Dylan opted for two-toned trunks.

Zac, 35, and Dylan, 31, both flashed big smiles for the camera despite the gloomy weather.

In the second snap, the former teen heartthrob fixed his hair after emerging from the water.

Zac also included photos of himself golfing — and getting swept up in a wave — in the carousel, which he simply captioned, “8/31/23.”

The thirst traps sent the “High School Musical” star’s 61 million followers into a frenzy given his lack of social media activity throughout the summer.

“saving *respectfully*,” one user commented, while another gave props to the pair’s parents, writing, “Nice genes, dad.”

“🥹I just want to be zaddy’s caddy 😂,” wrote a third, as a fourth joked, “Please lord my girlfriend cannot see this.”

“Kids wake up, Zac Efron grew his chest hair back,” someone else tweeted.

Zac has been making the most of his summer — all while seemingly never missing a workout.

The Emmy winner was spotted catching some rays with his pals on a luxury yacht in St. Tropez in July.

In photos obtained by Page Six exclusively, the shirtless actor showed off his six-pack abs and buff biceps while lathering up his tanned — and toned — body with sunscreen.

Despite maintaining a seemingly flawless physique, Zac previously admitted that he took things a little too far while training for “Baywatch” in 2017.

In order to achieve such a lean look, he worked out excessively and ate the same meal three times a day, which he said led to insomnia and “pretty bad” depression.

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“That [look], I don’t know if that’s really attainable. There’s just too little water in the skin,” the “Down to Earth” host told Men’s Health in September 2022.

“Like, it’s fake; it looks CGI’d. And that required Lasix, powerful diuretics, to achieve. So I don’t need to do that. I much prefer to have an extra, you know, 2 to 3 percent body fat.”

After filming, Zac decided to “let [himself] go” but quickly realized he needed a bit more structure.

“My body would not feel healthy; I just didn’t feel alive. I felt bogged down and slow.”

Whatever he’s doing now, it’s clearing working!