In the clip, posted on The Saturdays' star's Instagram account, topless Marvin encourages seven-month-old Alaia-Mai across the pool in her red swimsuit with white hearts on.
Protected from the blazing sun with a pink hat, she kicks her legs and happily splashes in the water.
Rochelle then snaps her daughter sat in a pink inflatable as she encourages Marvin to push her across the clear water.
Marvin, who last week performed with his JLS bandmates for the last time, recently said he's obsessed with his first born and would love another baby in the next couple of years.
He told NOW: "I can't wait - we want to have a big family. "Alaia is a fantastic baby - I'm obsessed with her.
"She's so cuddly and lovely. Even if she wakes me up at three in the morning, I love it!"