Riverdale's KJ Apa and Cole Sprouse party in Queenstown

Riverdale stars KJ Apa and Cole Sprouse are in Queenstown for the end of 2018, documenting their partying on Instagram.

Apa, a former Shortland Street actor, posted footage of his Italy-born US co-star Sprouse riding a mechanical bull at the tourist town's Cowboys bar.

The pair spent the weekend at Auckland's Hidden Valley Festival, a George FM gig, before heading south.

On Sunday, Sprouse published a photo at an Auckland Airport's domestic terminal captioned 'we made it', before Apa posted footage of them driving along what appears to be Queenstown's Frankton Rd.

Later in the evening, the 21-year-old Kiwi star posted several videos of his friends and himself riding the Cowboys bucking bull, along with the crowd watching and a photo of the bar's DJ.

Cole Sprouse wears Pornhub sunnies in KJ Apa photo posted from Queenstown, New Zealand, New Year's Eve 2019.
Photo credit: Instagram / KJ Apa

Sprouse wears Pornhub-branded sunglasses in some of Apa's photos and videos.

It's not known where the famous travellers will be partying for New Year's Eve.