iiNet founder Michael Malone has resigned as chief executive of the internet service provider, saying he wishes to dedicate his time to other passions.
Mr Malone has been on extended leave since November last year but had been expected to return to work within months.
He said he left iiNet in the strongest financial shape it had ever been in and with a strong growth plan for future success.
Mr Malone said he had reached his decision while spending three weeks climbing mountains in Argentina.
"Three weeks wandering around on a mountain with no telephone access or internet access gives you a lot of time to think and reflect on where I wanted to go in the future," he told reporters during a conference call.
"Having done that...the thought of coming back to doing this 9 to 5 just didn't thrill me."
He admitted there had been some "implied pressure" from the board to make up his mind one way or the other about his future at the company during his extended sabbatical.
"The business is in a bit of limbo unless I'm absolutely committed to returning to the role," he said.
"I think it was far better to put my resignation on the table and give everyone a bit of certainty. I was 90 per cent sure anyway that there was no chance I was going to come back and I'd discussed that with (iiNet chairman Michael Smith)."
He was named First Amongst Equals in Business News' 40under40 awards in 2006.
Mr Malone said it would be difficult for him to move on from the role but he planned to maintain a close relationship with the company.
He said he couldn't guarantee he would hang on to his nine million shares in the company he founded, which at today's share price of $7.67 are worth just more than $69 million.
"We don't know how Michael has managed to sustain his passion over such a long time and we are incredibly proud of his achievements," Mr Smith said.
"We are committed to ensuring his legacy and story lives on through a continued commitment to service excellence, challenging the status quo, thinking for ourselves and growing."
"If that turns out to be David (Buckingham), we will be delighted."
iiNet will appoint a firm to lead the search in the next few days and hopes to conclude the process by the end of the financial year.