As the train to Ronkonkoma pulled into Penn Station, Jason Lockhorn threw his arms up, bending his elbows like goal posts. But he wasn’t a frustrated commuter. He was dancing.

And he wasn’t the only one. Nearby, a man and woman twirled in the sinuous style of partner dance called Brazilian Zouk and groups of K-pop dancers swerved their hips in unison. Passengers flowed out of elevators, some stopping to watch, some rushing by with their luggage.

“If you ever want to find the culmination of what New York is as a culture, but expressing itself through dance,” Lockhorn, 24, said, “this is a good place to find it.”

Penn Station, the transit hub for hurrying commuters and Amtrak riders, has a side gig. Its wide, lower level corridor — specifically the passageway leading to the Moynihan Train Hall from Track 7 to Track 16 of the Long Island Rail Road — is an unlikely dance studio.

Officially called the West End Concourse, the corridor has a lot going for it: It’s easily accessible, the floors are spacious and smooth, and there are public restrooms, a rarity in New York City.

It’s a ready-made stage for all sorts of group and partnered dance, including hip-hop, K-pop and salsa. Reflective glass windows overlooking the tracks double as mirrors. Rows of blue lights overhead make for pleasing visuals when filmed. The biggest draw? It’s free.