Who does it belong to? Why is it there?
Well, now we can tell you.
It belongs to one of the pool's most dedicated patrons, Mackenzie Green.
Since she was a teenager, the 70-year-old has been swimming at the pool almost every day of its five-month seasons, walking to and from the pool from her nearby house, wearing nothing but togs and dressing gown.
"I'm deprived if I can't get my swim.
"It's absolutely good for the soul and the health.
"It's very therapeutic," she said.
Mrs Green credits the pool with helping her to regain her strength and health after a double mastectomy to treat breast cancer.
Her passion is such that she has helped to fundraise for the first, second and third developments of the pool.
"Without the pool, I might have had other, worse health problems."
At this time every year, she laments the pool's closure for the season.
To mark the annual event, Mrs Green went for two swims at the pool yesterday, before the doors were officially shut for the winter.
Pool supervisor Gaye Brooks said she was pleased with the number of people who had used the facility this season.
"Visitor numbers were down by about 4000 in January, due to poor weather.
But numbers were up by 3500 in February because the weather was so good.
"It's on a par with previous years."
The St Clair Hot Salt Water Pool would be closed until October 23, but the cafe would remain open, she said.
Until then, Mrs Green said she would make her daily trip to Moana Pool instead.
And depending on how late she is running, she may still wear her dressing gown.
