“SuperKai,” and “Old man and the pea,” the proud papa, 49, captioned the snaps.
Earlier this moth, the Salt actor posted a photo fishing with his elder son.
Last month, the father-of-two reunited with ex-partner Naomi Watts at Sasha‘s tenth birthday party.
“Happy Birthday Big Boy! Finally hit the double digits!” Schreiber captioned the image from their son’s birthday bash.
The Ring actress, 48, also shared birthday greetings for Sasha.
“Happy Birthday to this beautiful boy. Sasha is 10 today. Here he is in Africa, living his dream. His love and understanding of nature is everything. So lucky to be his mummy such a [gift] #inhiselement,” she captioned the image.
The former couple announced their separation in September.
“Right now I’m at a point where I’m healing and just wanting to protect the family unit, and we’re doing, so far, a pretty good job with that,” the Birdman actress recently shared. “We have huge love and respect for one another and high hopes for it to remain that way going forward.”