A 79-year-old sailor is attempting to sail solo more than 15,000 nautical miles from Dingle, Co Kerry to New Zealand.
The well known Swedish sailor and writer, known as Yrvind, hopes to complete the epic voyage in just over 300 days.
The sailor has built his own boat for the challenge, a 19ft composite low energy craft.
This morning, the vessel called Exlex (Outlaw) was towed by a Dingle fishing boat to its departure point just west of the Blasket Islands.
Yrvind, whose name translates as "whirlwind", will not set foot on land again before he reaches Dunedin in New Zealand.
He has enough food on board for 360 days and water supply for four months.
He has plans to harvest rain water, and his diet will consist of calorie-rich muesli, sardines and rye bread.
The route will see Yrvind sail south across the equator before rounding the Cape of Good Hope at the southern tip of Africa and then across the vast Southern Ocean.
He will sail south of Australia before finally making landfall in Dunedin, New Zealand.
Speaking before his departure, Yrvind said he was looking forward to the challenge following three years designing and building his boat.
"It will be the ultimate test of the craft I have built. I am happy with it but I admit it is an experiment. The boat will be really tested, especially in the Southern Ocean," he said.
Yrvind believes the greatest dangers will lie in the threat of pirates off the west coast of Africa, cleaning the hull of his boat in shark-infested waters and icebergs in the Southern Ocean.
"I will celebrate my 80th birthday during this trip but physically I am in very good condition. I feel strong. I also have the added benefit of many years of experience." he added.
The renowned sailor has completed many long-distance solo attempts in the past, including sailing across the Atlantic, around Cape Horn and landing on some of the most remote islands in the Pacific Ocean.
"I am a recluse. I enjoy being alone. After one month at sea something strange happens. I become like an animal or a bird. Like an albatross. It is ultimate freedom."
Yrvind plans to spend most of his time below deck in a 3ft x 10ft x 2ft water-tight cabin.
The unique vessel will be propelled by 4sqm of sail and will be steered by rope-operated twin rudders.
Yrvind's progress can be tracked on his website.