Pop star Justin Bieber stripped to his underwear to go for an impromptu swim in a glacial river during his trip to Iceland.

The Baby singer is reportedly in the country to work on a new music video and he shared pictures of the trip online.

During his visit, Bieber peeled off his clothes on a riverbank and waded into an icy river for a swim wearing nothing but his Calvin Klein boxer shorts.

He uploaded a picture to Instagram.com showing himself soaking wet and high-fiving a pal, along with the caption: "Glacier dip in #iceland (sic)."

Local reports suggest Bieber is in Iceland to film a video for a new single, following on from the success of his comeback record What Do You Mean?, which became a number one hit across the globe following its release earlier this month (Sep15).

The song was the U.K.'s fastest-selling single of 2015 so far, and his first number there. It is taken from his currently-untitled fourth studio album, which is slated for release in November (15).