Holy biceps! Zac Efron [1] put his insanely buff body on display during a swimming lesson in LA on Thursday. The actor sported a swim cap and goggles for the pool day, and was joined by what appeared to be a bodysuit-clad instructor; it's likely that Zac is learning some important water moves before he starts filming the Baywatch movie with fellow muscle man Dwayne Johnson [2].

Zac has been busy promoting his current movie, Dirty Grandpa [3], which he stars in with Robert De Niro [4] and Aubrey Plaza; he recently stopped by Jimmy Kimmel Live [5] to watch a cringeworthy video of himself in high school (and shared a sexy shirtless snap [6] while backstage), and charmed Ellen DeGeneres during a game of Heads Up! [7] when he twerked and gave her a steamy lap dance. Keep reading to see photos of Zac's day in the water, then check out 74 crucial moments from your decades-long crush [8] on him.