"Sarah has been scuba diving for about eight years now, and I've always been interested but never taken the time to get certified," Markie told BuzzFeed News.

Markie spent a month secretly taking scuba diving lessons so she could surprise Sarah underwater.

"I work in film, so working long hours on short notice isn't shocking," Markie said.

"I was getting up very early, going to a friend's house to get all my gear, going to classes and doing dives, then coming back to the friend's house, showering, completely drying my hair, and then putting product in so it didn't look like I'd just washed my hair, then going home."