Lana Del Rey joined Jack Antonoff last night (April 15) to perform her ‘Did you know that there’s a tunnel under Ocean Blvd’ collaboration ‘Margaret’ for the first time.The singer-songwriter joined the Bleachers frontman onstage for their High Water Festival show at Riverfront Park in North Charleston.While the rest of the band watched on Del Rey and Antonoff swapped vocals on the track, while the latter strummed an acoustic guitar. You can listen to it below.The collaboration with Bleachers is about Antonoff’s fiancée, the actor Margaret Qualley, Del Rey previously revealed.“I was like, ‘You know what? I want to write a song for him.’ It lands right in the middle of the album.