The 23-year-old, who has lived in the resort since February, told Mountain Scene he did not realise his actions could have resulted in serious injury or legal action.
He admitted the decision was "silly'' and "reckless''.
"I just thought I was having fun. I didn't realise it was a criminal offence.
"There was a bit of banter with my mates beforehand ... and I guess that is pretty much why I did it.''
However, senior launchmaster Peter Greer, of Real Journeys, points to the serious nature of Mr Murray's actions.
The British national could have been sucked under the propeller blades and the steamship had little control without them.
"It was a reckless things to do, not only endangering his own life but potentially the other 300 people on board. We appreciate him coming forward and accept his apology but it is illegal and is no joke.''
Queenstown harbourmaster Marty Black was not impressed and described it as "sheer stupidity''. Murray has also apologised in writing to the tour operator.
He warned others not to do what he did.
"Setting a bad example for others who might not be as lucky if they copy my actions.''
Maritime NZ spokesman Vince Cholewa confirmed the agency was not taking any action against Murray.
