Amber Bourke is aiming for a podium finish when she competes at the Freediving Pool World Championships in Serbia in June.
Amber, 25, of Birkdale, participates in both depth and pool freediving, and qualified for automatic entry into this year's pool world championships by finishing in the world's top 10 last year.
Pool freediving tests the distance a competitor can swim under water, and competitions are run with and without fins.
At the last world champs in 2013, Amber was third in the no-fin event and qualified for the final with fin. This year, she hopes to do even better.
She set national records in both events in 2013, with distances of 200m with fin and 164m no-fin.
Amber is gearing up for the next national competition in Gladstone in May, in the lead-up to June's world champs.
From there, she will turn her attention to the depth freediving national champs, to be held in Bali in August, where she will aim to better her 53m best dive.
Depth freediving events are held in the sea or in deep lakes and Amber said while Australia had plenty of coastline, there was nowhere suitable for free-diving.
"The Australian nationals have to be held in Bali because it's the nearest suitable location without dangerous currents," she said.
Depth freediving involves competitors descending as deep as they can, following a line in the water. It can be dangerous and a host of safety measures are in place during the competition.
"We are attached by a lanyard so we are always connected to the line and can be helped to the surface quickly if we need to," she said.
"The most dangerous time is the last 15 metres on the way back up, so during competition there are safety divers in place to keep an eye on us."
Although she enjoys all water sports, especially wakeboarding and ocean swimming, Amber initially specialised in synchronised swimming.
"Freediving is breath-hold diving, and with synchronised swimming I found I was good at holding my breath," she said.
In the lead-up to the competitions, Amber trains up to 10 hours a week with the Brisbane Freedivers Club at the Sleeman Aquatic Centre, juggling training with full-time work as an electrician.
Her preparation will involve cutting back on swimming training to concentrate on breath-holding under strict supervision.
Amber is acutely aware of the dangers of breath-holding.
"Freedive training should never be done alone," she said.
"It is an important safety requirement for anyone undertaking any sort of breath-holding in the water to be supervised.
"It is our number one rule to always have a buddy."