Cousins’ first photo! Princess Eugenie celebrated Earth Day on Saturday with a sweet snapshot of her son August Brooksbank with her niece Sienna Elizabeth Mapelli Mozzi. “It’s World Earth Day and today is all about celebrating our planet and people doing amazing things that help protect it,” Eugenie wrote alongside the Instagram carousel.

The first photo shows August and his younger cousin Sienna—who is the daughter of Princess Eugenie’s sister Princess Beatrice and Edoardo Mapelli Mozzi— standing next to each other as they watched penguins at the London Zoo. Eugenie revealed in the caption that her son and niece “love going to the London Zoo.”

She added, “It’s part of the Zoological Society of London @zsllondonzoo a global wildlife conservation charity that helps to restore habitats and protect wildlife. Every time you visit you are supporting their work.”

Eugenie also included photos of her two-year-old son at the BBC Earth Experience in her Instagram carousel. “Their vision is to inspire visitors to protect the planet through this immersive experience,” the Princess noted of the experience.

The last image she included was one of August and her husband Jack Brooksbank strolling together outdoors. “Because I love them and they love nature,” she wrote of the picture.

Eugenie and Jack are expecting their second child this year. The Princess announced the news in January with a photo of August kissing her baby bump, which she captioned: “We’re so excited to share that there will be a new addition to our family this summer.”