The fourth season of the reality show kicked off last night, and within the first few minutes, three recruits had already called it a day.

28 civilian recruits boarded the bus to hell on last night's season premiere of 'Special Forces - Ultimate Hell Week' on RTÉ 2. And oh boy was it a tough start to the series. Catch some of the reactions from viewers below.

Within the first five minutes, we already had our first casualty after the DS raided the bus carrying the fresh batch of contestants. Two minutes later, another recruit dropped out due to an injury and by the end of the opening 15 minutes, there were 25 civilians left standing.

The series sees people from all walks of life - but who have a particular endurance for the cold, exercise, getting shouted at, and generally just feeling like sh*t - attempt to last for just one week only on Ireland's most soul-breaking experience ever.

Now in it's fourth season, and with a failure rate of upwards of 90%, only the toughest candidates will survive. Over seven days, the recruits will be required to pass numerous rigorous physical and mental tests, and in last night's opening episode we saw the recruits nearly freeze to their bones as they attempted to keep up with the outlandish tasks concocted by the DS.

Rule number one for the new recruits - no smiling or laughing. This was put to the test when one of the contestants had to begin dancing for his comrades, which bore striking similarities to one particular scene from 'Father Ted'.

The episode all came to a head in what was a spectacularly jaw-dropping moment. Some of the recruits were dragged into a room where the DS chatted with them.

Recruit number eight's head was covered, he was dragged into a room full of the DS, and was then unmasked. However, the episode ended with him laughing, saying "You shower of f***ers". Do we have a spy in our midst...?

Here's how viewers reacted to 'Ultimate Hell Week' being back on RTÉ 2.

'Special Forces - Ultimate Hell Week' continues Thursday nights on RTÉ 2 at 9.30 pm. Catch up via the RTÉ Player.