Gavin Noble finished 23rd of 55 competitors in the men's triathlon
event at the Olympic Games.
The Enniskillen man started strongly and lay in 15th position after the 1.5km swim, 28 seconds off the lead.
Noble, 31, improved to 11th place after the 43km cycle, three seconds off the lead, having led for a short period.
He fell back during the 10km run and finished in a time of 1:49:47, three minutes 22 seconds behind the gold medallist, Team GB's Alistair Brownlee.
Javier Gomez of Spain won the silver medal, with Jonathan Brownlee in the bronze medal position.
Fermanagh-born competitor Noble became the first Irishman to participate in an Olympic Triathlon when he lined up for the start at Hyde Park in London and he described the event as a "wonderful experience".
The 31-year-old has been bothered by injury in the build-up to the Games but he insisted that he would have only positive memories of his Olympics.
"If in two weeks, two months or 10 years, someone asks me about the the Olympics, I'm not going to bang on about having a sore leg," said Noble.
"If there are young guys out there in Ireland who are thinking about going to the Olympics, I'll tell them to embrace it and give up everything and pursue it relentlessly.
"I had a great swim. I was lucky that I had some good swimmers around me and we avoided the fighting.
"By the end of the first lap (of the bike ride), the opportunity for a top-25 finish was there.
"In reality, I wasn't coming here for the medal but was hoping for the highest place I could.
"It's a marker in the sand for other Irish athletes. I'm the first of many."
Noble added that he was looking forward to "enjoying the remainder of the Games and getting to the village and seeing my family".
"I'm also looking forward to eating proper food and becoming healthy again".