Ms Robertson, 22, is wearing the head turning swimwear in the photo above.
"I guess it is controversial," she said.
"It's a high-cut G-string bikini. It's very naughty. It's from a Byron Bay-based swimwear company - girls in Ralph often wear them."
Ms Robertson, of Nightcliff, is a finalist for the Miss Hahn Super Dry competition grand final tonight.
But she won't be donning her signature bikini - she is instead opting for a black pirate-themed garment adorned with skulls.
She said it was the theme wear category she was most proud of.
"A very good friend of mine, Matilda Alegria, made the outfit for me," she said. "It's themed on the dragonfly.
"They are an enormous part of Darwin - the first thing you see for the Dry."
Ms Robertson will be vying for the title of Miss Hahn Super Dry tonight. The competition kicks off at The Deck at 6.30pm.
modelling and controversy.