More than 2,000 competitors will put their bodies to the test this weekend in the capital's second annual Ironman 70.3 event.
A number of professional endurance athletes are among those who have signed up to take part in the race - including triathlete and former Leeds United footballer Bryan McCrystal.
One competitor who registered yesterday was Landon Cassill - a well-known professional Nascar racer in the US.
The 27-year-old, originally from Iowa, told the Herald he would participate with his father Roger.
He picked the Dublin event because it was on during a break in his busy stock car schedule.
"I'm an avid Ironman triathlete. My parents and my wife had Ireland on their bucket lists, so it worked out perfectly," Mr Cassill said.
"We've been here most of the week and we're leaving next Tuesday. We love it here, there is so much history and we gravitate to places like that."
The race car driver explained how this was his fifth Ironman 70.3 event.
"Race car driving is an endurance sport and I think training for the Ironman helps with the mental and physical aspect," he said.
He will be joined by TV3 weather presenter Deric Hartigan, former Irish contestant on the Biggest Loser UK show Gerard Burke and personal trainer and sports columnist Karl Henry when the race kicks off tomorrow morning.
Last year, Voice of Ireland judge Bressie managed to finish the gruelling race, which was the first Ironman 70.3 event to take place in the capital.
This year's race is a half Ironman event, and the athletes will have to undertake a 1.2km swim in Dun Laoghaire bay, a 90km cycling loop from there through the city centre and into north Dublin. It will finish with a 21.1km run around the Phoenix Park.
Meanwhile, organisers have said they are monitoring the presence of dangerous jellyfish in Sandycove.
Dun Laoghaire-Rathdown County Council advised bathers to stay out of the water due to the presence of lion's mane jellyfish. In a tweet, the Ironman's organisers said "athlete safety is paramount" and they will "take action if necessary".
The event kicks off with an early morning swim at 6.50am.