We've known for quite some time that Kim Kardashian and Kanye West's daughter Nori is obsessed with mermaids, as is Kourtney Kardashian and Scott Disick's little girl, Penelope. On Saturday the girls celebrated their birthdays with a joint mermaid-themed party, and it looks like the family had a blast!

Nori turned 3 on June 15, and Penelope will turn 4 on July 8, and the tots rocked elaborate costumes and enjoyed not one but two custom birthday cakes. Kim wore a mermaid inspired outfit, and Khloe took things one step further and wore a bright pink wig. “Normally it’s Kylie in a wig!” Khloe later joked on Instagram.

Kim didn't post many photos from the bash, but Kylie and Khloe were Snapping and Instagramming the event, and she took some time to pose with Mason and both of the birthday girls. Aww!