“Casual wave and an air kiss,” the Younger star, 29, captioned the video of her son riding behind a boat.
Before hitting the water, the single mom posted a photo with her son flying to their destination.
On Mother’s Day, the singer-actress shared a snapshot and heartfelt message.
“Best thing that ever ever happened to me. I got the privilege of becoming a mother… and everyday I am grateful for his [light]. #happymothersday to every mom out there that feels the same as I do . A mothers job is never done. But what a rewarding job it is,” she wrote.
Duff welcomed Luca with ex-husband, former NHL star Mike Comrie.
❤️✈️ A post shared by Hilary Duff (@hilaryduff) on