After 18 months of training, the 21-year-old landed in Adelaide yesterday for his first open world championships with the Black Fins.
Trembath is one of two St Clair representatives in the squad of 12 - Commonwealth Games swimmer Carina Doyle is the other.
Both are now based in Auckland, although they have retained their southern connection.
It had been a long preparation, and Trembath was excited to have arrived.
''It's good to finally get here,'' he said.
''It's been a long build-up, just grinding away since halfway through last year when we started.
''To get here and put it all together and to get in the team environment is really exciting.''
It was not Trembath's first big meeting, although it would be his first on this stage.
Among those he had been to were the junior world championships and world games.
However, the open world championships were the pinnacle, and he was hoping to help New Zealand win its fourth consecutive title.
He would compete in the pool events, as well as the tube rescue at the beach.
While doing well in everything was a goal, his main focus was on performing well to help the team.
''A big thing for me will be trying to make every A final.
''It is a points-based competition and if you can get two New Zealand athletes in the A final and other countries don't, it can really create a big buffer.
''So if I can put the race together I should definitely be able to get into those A finals and get some points.''
The majority of Trembath's training took place in the pool.
He continues to swim for the North Shore club and was training 10 times a week plus gym sessions for that.
On top of that he was adding another three sessions for surf lifesaving training.
The two complemented each other well, and swimming itself had taken him to events such as the Oceania Championships, Junior Pan Pacific Championships and an altitude camp in the USA.
However, having just finished his construction degree at Massey University, he would have to decide whether to carry on with that or just focus on surf once he became full-time employed.
It was in the surf lifesaving that his passion lay.
He will get the chance to win a world championship in that on Tuesday, as he competes against 4000 athletes from 44 countries over the next two weeks.
