Paris Hilton threw a big party to celebrate her baby boy Phoenix’s first birthday. The theme was ‘Sliving Under the Sea,’ and stars like Kelly Osbourne and Rumer Willis joined the fun at her house.

In videos from the party, Hilton’s backyard looked like an underwater world with fish-shaped balloons and seaweed decorations. There were white seats shaped like coral with starfish cushions, and music from The Little Mermaid played in the background.

Hilton, who turned one on January 16, explained the theme, saying, “It’s Phoenix’s first birthday, and we have a ‘Sliving Under the Sea’ theme. I’m so excited. I’ve thrown amazing birthday parties my whole life, so to now be able to do this for my little boy is such a special memory.”

She carried Phoenix outside, showing him the decorations, and said, “Look, this is all for you! Yay!” Many guests attended, including Kelly Osbourne, Rumer Willis, Lance Bass, Kat Von D, and model Jessica Hart. The party had a petting zoo with sheep, bunnies, baby goats, chickens, and even a unicorn.

Hilton has two kids, Phoenix and London Marilyn, who is 2 months old, with husband Carter Reum. Both children were born via surrogate. Hilton shared a birthday tribute on Instagram, calling Phoenix a “dream come true” and expressing gratitude for being his mommy.