Kendall Jenner, Jacob Elordi and Justin and Hailey Bieber held their own exclusive event in Idaho as Taylor Swift was getting hitched to Travis Kelce in NYC.

TMZ obtained video showing Kendall, Jacob, Justin and Hailey piling into a speed boat docked at Kendall's lake house in Coeur d’Alene, ID, -- a luxurious rustic community where A-list celebs go to kick back, relax and even play golf at Gozzer Ranch nearby. 

As you can see from the footage, shot Friday afternoon by an eyewitness, the two famous couples cruise away on their motorboat and they seem totally chill, having a grand ol' time.

The witness tells us Jacob, Kendall, and the Biebers were passengers with three others were on the boat, including one person steering it.

Their private outing came around the same time Taylor and Travis were getting married at their closed-door event in Manhattan with major security provided by the NYPD. 

As the world knows, Taylor and Travis said their "I Do's" inside the iconic Madison Square Garden before hundreds of celebs and family members.

Some of the big-name attendees were Jennifer Lopez, Tom Cruise, Tom Hanks, Stevie Nicks, Paul McCartney, Selena Gomez, and Bradley Cooper and Gigi Hadid who we caught heading out the door for Taylor and Travis's big day.

No word on if Kendall, Jacob, Justin, and Hailey got the invite to the nuptials in the first place.

An invite for Kendall would be a pretty big olive branch on Taylor's part ... her 'Reputation' era was sparked by the feud heard round the world between her and Kim Kardashian and Kanye West over the notorious "Famous" phone call.

Of course, an invite for The Biebers would have pretty much guaranteed the couple crossing paths with Justin's ex Selena.