Derval O'Rourke tonight became the first coach in Ireland's Fittest Family history to have four out of four families make it through to the quarter-finals of the show.
This evening's episode saw Derval and the Kulczynski family waltz into the quarter-finals of the competition.
Fellow coaches Donncha O’Callaghan, Anna Geary and Davy Fitzgerald have seen one family each through to the next stage.
Viewers watched on as Sabien Kulczynski gave a stellar performance where he held on to a log for the longest time of 37 minutes and 25 seconds for the Bog Bath challenge.
Other challenges in tonight's episode were Fast and Furious and the Eliminator.
Fast and Furious tested the families in speed, agility and endurance.
A head-to-head 200m relay race saw the competitors jumping over hay bales and contending with other obstacles.
Once each member of the family had completed the course, all four had to rerun the length of the course up and down and climb back up to their starting position.
Anna's Bracken family were victorious and went straight through to the quarter-finals while the remaining two battled it out in the Eliminator to claim the final spot.
During the Fast and Furious challenge, Jamie O'Halloran injured himself and was taken to hospital for precautionary measures. With Jamie out of the Eliminator, both families went down to three members each.
Donncha's O'Halloran family and the Kulczynskis went head-to-head in the final challenge which took place deep in the forest.
Each of the families jumped off hay bales before collecting a log and running through the forest.
They faced a number of obstacles including tyres and a cargo crawl net and even an ice-cold plunge bath.
The Kulczynskis were victorious and sealed their place in next week's show.
This week's episode saw Davy Fitzgerald's Kelly family and Donncha's O'Halloran family eliminated.
Ireland's Fittest Family airs on Sunday at 6.30pm on RTÉ One.