The 43-year-old star said that it was the first time his mother decided to conquer her fears and get into the ocean.
"63 years of waterphobia. Never swam. Today she jumps off a boat into the deep Indian Ocean. Here she is flying beyond the fear. So proud of you mama!" Hrithik tweeted, along with an underwater shot of his mom.
The actor was last seen in Sanjay Gupta's "Kaabil," which released in January this year.
Hrithik received rave reviews for his portrayal of a blind man.