Soaring thousands of metres in the air on a flight from New Zealand to Singapore, Mr Grant Rawlinson is preoccupied by what is beneath him.
He completed an expedition in 2013 to summit the highest peaks in the North and South Island but his adventurous soul is again restless.
Instead of a plane, he thought, why not try making this journey by land and sea?
Two years of planning later, the grand quest will become reality.
On Jan 3, the Singapore permanent resident will set off on a 12,000km trip spanning almost a year aptly titled "Rowing from Home to Home".
Mr Rawlinson will attempt to row his $120,000 Ocean Rowing Boat 4,500km from Singapore, through the Indonesian archipelago and across to Darwin in Australia's Northern Territory.
The Kiwi will then cycle 4,500km south-eastwards to Coffs Harbour in New South Wales, while the boat will be shipped to the end of the cycling stage.
He will then row another 3,000km across the Tasman Sea to New Plymouth, in Taranaki.
"From there, it's just a 40km cycle back to my parents' house in Stratford," chuckled Mr Rawlinson last week at Raffles Marina.
"Hopefully I'll be home in time for Christmas."
He added to The Sunday Times: "No one to my knowledge has tried rowing this route before, so there are a lot of unknowns. There are no log books to reference and it's taken years of research to plan this entire trip."
Improbable as his goal may sound, the 42-year-old, who quit his job as a regional sales manager to focus on this trip, betrays little in terms of doubt.
After all, more than a decade of climbing mountains around the world - he scaled Mount Everest in 2012 - has taught him that no peak cannot be reached.
The budget for the expedition is $250,000, part of it covered by several sponsors.
There is neither silverware nor fame at the end of this personal undertaking, only the quiet satisfaction that explorers like Mr Rawlinson search for.
The former Singapore national rugby sevens player said: "Doing this is really about the journey and not the destination. I believe we are all capable of great things if we are willing to push our limits."
The physical toll will be immense. During the first leg from Singapore to Australia, both Mr Rawlinson and team-mate Charlie Smith will alternate one- to two-hour shifts, rowing non-stop for weeks.
One will rest in the narrow cabin while the other drives the 750kg (including supplies) fibreglass vessel forward.
They estimate that it would take them a month to reach Bali, where they will rest for about a week.
Mr Rawlinson's wife Stephanie and one-year-old twins Rachel and Kate will meet them there.
Mr Smith, a 26-year-old Englishman who works in Singapore as a project manager, said: "We hope to row at speeds of about 4-5kmh, which in good conditions could see us cover as much as 100km a day."
He will take part only in the first rowing leg. He was introduced to Mr Rawlinson last year by a mutual acquaintance and jumped at the chance to join the "once-in-a-lifetime" expedition.
An intensive training regimen over the past year has seen Mr Smith add 11kg to his previous 84kg frame, strength that will come in handy for the arduous work ahead.
They will carry two sets of clothing and about 150kg of food - mostly freeze-dried meals that range from curries to roast lamb and pasta - that can last roughly 40 days and will consume about 6,000 worth of calories each day.
Both men expect to expend a similar amount of calories every day by rowing.
Mr Smith, who was an avid ice-climber in England, added: "This will be by far the most physically demanding thing I've ever done."
Both men have clocked more than 300 hours in training.
They have rowed around Singapore twice and to Bintan and Batam, and spent a week at sea together.
Yet no amount of practice prepares someone for the vulnerability of crossing an ocean in a 6.8m craft powered by oars with a rear-view mirror fixed at the stern; they row backwards after all.
"There are so many dangers out there," said Mr Rawlinson.
"We could get hit by a ship, get swept into a bad storm, break our equipment, fall sick or run into pirates. You really don't know what to expect."
At least the boat is equipped with the latest technology to give them every chance to succeed.
Solar panels at both ends of the craft generate power for a host of electrical devices, including a pump that converts sea water to potable water, a GPS tracking device which emits their location every 15 minutes and a satellite communications terminal for daily weather updates.
It can get very lonely out there surrounded by such vastness, though Mr Rawlinson seems to relish the long hours of introspection.
This will be life stripped down to its barest form, he said.
"You eat, sleep and row."
The reason was simple.
As French Nobel Prize-winning author Andre Gide once wrote: "One does not discover new lands without first consenting to lose sight of the shore."
This article was first published on December 25, 2016. Get a copy of The Straits Times or go to straitstimes.com for more stories.