At 23m high, how does this floating artwork stand up?

How to unveil a public sculpture when it's 23 metres high and floating on Sydney Harbour?

Just installed at Watermans Cove in Barangaroo South, Monuments for Fishes by artist Mikala Dwyer is one of the biggest floating kinetic sculptures in the world.

It's made up of five towering spires, each designed to sway with the wind, rise and fall with the tides, and light up at night to create reflections on the water.

Inspired by fishing floats, Dwyer came up with the concept for the artwork 14 years ago.

Seeing it finally in place ahead of its official launch, she couldn't quite believe her idea had finally become a reality.

"I was a bit shocked and a bit numb, I was just sitting there thinking it just all looks so fake, I don't believe it," the artist told AAP.

She has a point - on first sight, the sculpture is so tall it seems it should fall over at any moment.

But Monuments for Fishes is not only an artwork, it's a feat of engineering, with about 100 people involved in the project.

Under the surface of the water there's a six and a half metre steel keel as well as six buoyancy modules that stabilise Monuments for Fishes and keep it afloat.

It's all attached to a steel pile that's secured into the seabed, preventing the artwork floating away.

At least seven different engineering specialties, and tradespeople such as shipwrights, spray-painters and steel welders, were needed to bring about Dwyer's artistic vision.

The artwork was crafted from steel, fibreglass and carbon fibre, the same materials used in yacht building.

Each tower is designed to move autonomously in response to its environment, explained Event Engineering director Jeremy Sparks.

"They go up and down with the tide, they move and list and pitch and yaw depending on the wind and the waves," he said.

Importantly, they are also designed to be unsinkable, he said.

Sparks' company has worked on dozens of public art projects across Australia, such as Dark Mofo's Ogoh Ogoh Willow Tree in Hobart and a Squid Game doll installed in Melbourne's Federation Square in 2025.

"It's a Pizza Hut of crazy ideas ... We're problem junkies, I guess is the best word for it."

The monuments are the fifth and final permanent public artwork installed as part of the Barangaroo precinct development.