Keen-eyed residents of Caloundra have been surprised by an unusual sight off the coast.
They were taken aback by a submarine making its way south on Thursday.
Among those to get a glimpse was regular photo of the day contributor Lesley Evans, who lives on top of the hill at Kings Beach.
“I saw it and notified a friend, who could see it from another angle, and we googled ‘submarines’. I was surprised, as it looked like something homemade.”
The vessel they spotted was in fact a guided-missile submarine that is a key part of the Australian Defence Force.
A Department of Defence spokesperson confirmed its presence and revealed its identity and objective.

“Defence can confirm that one of the Royal Australian Navy’s Collins-class submarines HMAS Dechaineux has ported in Brisbane,” they said.
“While in Brisbane, Dechaineux’s crew will be meeting and conducting submarine tours with Australian Defence Force candidates to give the future of Australia’s defence force an opportunity to learn more about life as a submariner.”
HMAS Dechaineux was commissioned in 2001 as one of six Collins-class submarines to enter service in the RAN.
It is based at Fleet Base West in Western Australia and has conducted a range of activities and operations.
It moves silently on diesel-electric power, supplied by banks of new-tech batteries charged by three on-board diesel generator sets.
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The combat system gathers intelligence from sensors, computes the input, and launces and directs weapons.
It has six torpedo tubes and can carry 22 torpedoes or 44 mines.
It is almost 78m long, can reach a speed of 20 knots submerged and 10 knots surfaced, and can accommodate 48 crew members plus about 10 trainees.
It’s not publicly known how deep it can dive but it has reached at least 180m (590 feet).
Its motto is ‘Fearless and Ferocious’ and it was named after Captain Emile Dechaineux, the commanding officer of HMAS Australia (II) in World War II.
The Collins-class submarines were designed by the Swedish Navy and are renowned for being quiet.
They include high-performance hull form, highly automated controls, low indiscretion rates, high shock resistance and an efficient weapons handling and discharge system.
Australia’s Collins-class submarine fleet will undergo a life-of-type extension from 2026 as the government ramps up its defence capabilities.
A focus of Defence is a multi-billion dollar project unveiled by Australia, the United States and the United Kingdom, which involves Australia acquiring nuclear-powered attack submarines.