Naomi Watts wishes son Sasha a happy 16th birthday: 'My darling boy'

Naomi Watts is wishing her son Sasha a happy 16th birthday.

The "Mulholland Drive" actress, 54, took to Instagram Tuesday to celebrate her eldest child's latest milestone with a heartfelt post featuring a carousel of photos of him throughout the years.

"Happy 16th to my darling boy," she wrote in the caption. "I cannot believe how fast this happened?! Beyond proud of the young man you've become with the most wonderful spirit, fantastic sense of humor and kind, compassionate soul."

She continued, "So lucky I get to be your mum. Thank you for still letting me hold your hand sometimes. Even though I know you probably just forget to pull it away. You blow me away!!"

In addition to Sasha, Watts is also mom to her youngest child Kai, who turned 14 in December. The Australian actress shares both children with ex-partner Liev Schreiber.

Schreiber, 55, also shared a birthday tribute for Sasha on Instagram. "Happy Birthday Handsome!" the "Scream" actor captioned a selfie of him and Sasha.

Watts confirmed last month that she and actor Billy Crudup tied the knot by sharing a photo of them in their wedding attire to Instagram. "Hitched!" she captioned the snap.