Gwillym became a movie editor, and worked on movies with James Cameron. He spent months on a boat by the Mariana trench for the Deepsea Challenge documentary.
One day he just started sky diving, Robyn Hewetson said.
"He went from skydiving to base jumping, and from base jumping to wingsuiting."
Frith Hewetson said despite Gwillym being away so much, he was incredibly close to her two sons, Rowan and Thaeo.
"After Mum and Dad, Uncle Gwill was number one."
"He's very present in both of their lives, despite the fact they've both had less than three days with him in the last three years."
His plan was to jump until age 40, and then he was going to settle down in Melbourne and start his own company.
For Gwillym, the jumping wasn't about an adrenaline rush, it was about moments of mindfulness and peacefulness.
"He wasn't ever scared when he did it," Frith Hewetson said.
Robyn Hewetson and her son Gwillym during their last visit together. Photo / Supplied
Robyn said her favourite memory of her son was earlier this year, when she saw him in Hawaii, where he was working as a professional skydiver.
"On February 21st this year, we did a tandem jump."
She said there was no way she would jump out of a plane with anyone else.
After the jump, the pair sat on the beach and ate fish tacos, when Gwill said something to his mother.
"He said, 'look Ma, I know you think you're frightened, you think you are a frightened person, but I watched you, I watched up growing up, you brought us up by yourself in a foreign country'."
"He said, 'you're the bravest woman I know, you taught me to be brave'."
The time in Hawaii was the last time they saw each other.
