Cousins who vacation together dress alike -- at least when you're North West and Penelope Disick you do.

Kim Kardashian shared a photo on Instagram of the 2-year-old and her 3-year-old niece, daughter of sister Kourtney Kardashian and Scott Disick, completely focused on a woman dressed as a mermaid in a swimming pool.

The toddlers are both pictured dressed as mermaids, wearing mermaid-like long skirts, North in a green one and Penelope in a pink one, and matching bikini tops.

Kardashian captioned the photo, which she posted on Aug. 18, with "Little Mermaids."

 Little mermaids

A photo posted by Kim Kardashian West (@kimkardashian) on Aug 18, 2015 at 7:11pm PDT

According to Popsugar, the Kardashian family are currently on vacation in St. Barts where they have been spotted participating in a variety of activities, including four-wheeling around the area, parasailing and spending time at the beach.

Currently expecting her second child with husband Kanye West, Kim Kardashian was also pictured barring her stomach while working out on the beach, reported E! Online.

The reality star recently made headlines by posting a nude selfie showing off her pregnant body to silence her critics and end rumours that she is faking her pregnancy.

"First they said I'm too skinny so I have to be faking it...Now they say I'm too big so I have to be faking it...SMH," Kardashian captioned the picture. "Some days I'm photographed before I eat & look smaller, some days I've just eaten & I look bigger. It's all a part of the process. I think you all know me well enough to know I would document the process if I got a surrogate. Everyone's body is different, every pregnancy is very different! I've learned to love my body at every stage!"