Through the pale water, the nondescript concrete blocks look out of place against the white seabed. But beneath the gentle swell, the lines are revealed as row after row of small pots, each growing a colourful piece of coral.
The remote 13.7ha site, in the pristine waters of the Abrolhos Islands, is the first farm of its kind in WA, growing coral for aquariums in open water.
It's the creation of third-generation fisherman Andrew Basile and his wife Tracey, designed to provide their children with an alternative business in the islands, should fishing one day become unviable.
After two years of collecting coral stock to propagate and perfecting the growing conditions, the Basiles have a welcome problem: the coral has grown as much in eight months as they expected in four years. Next month, when the tide and swells are low, they plan to expand, with their first sales next year.
Mr Basile's family have made a living in these waters, about 60km off the coast of Geraldton, for more than half a century. Home for the rock lobster season is Basile Island, named for Andrew's grandfather, and until the eldest went to high school, Mrs Basile home-schooled their three children so the family could live on the island full-time.
Now they live in Geraldton, running a tiling business, and Mr Basile goes back and forth. In the pre-dawn darkness on the tiny island, he sets out to pull in his craypots, as his father did before him.
The islands have changed in many ways in his lifetime but most noticeable is the plummeting population since crayfish catch limits were imposed in 2009. The school on Rat Island has finally closed and the carrier boats, which used to come to Basile Island every other day, no longer visit at all. Department of Fisheries figures show there are 79 vessels in the Abrolhos zone this season. Just five years ago there were 128.
"There used to be probably 40 or 50 permanents on the island, young families with kids," Mr Basile said. "It was a busy place and every camp would have somebody in it. These days, there might be eight of us."
But as one industry shrinks, others are springing up.
Nearby in the southern group, two sheds sit on jetties jutting out over the water. Inside one are gently bubbling tanks with millions of microscopic oysters and a laboratory filled with gently glowing algae-filled containers to feed them.
In the other, three Japanese technicians work with dental tools, seeding adult shells with tiny spheres of Mississippi clam shell, around which the oysters lay down layers of iridescent nacre to create a pearl.
For Murray Davidson, a shearer-turned-crayfisherman-turned-pearl farmer, it was a dream to have a hatchery to grow the strongest possible shell, rather than relying on wild stock. He now manages this farm and hatchery, headed by Tracey Basile's father, Barry Humfrey.
They grow traditional black lip oysters but the buzz is about a new market: Akoya pearls, once considered a nuisance but prized by the Japanese. This year, the farm is preparing for its first commercial harvest. "We have beautiful water here and that helps us a lot," Mr Davidson said. "We started with the wild Akoya shell and the pearls were good but I believe the hatchery shell is better. The black lip is a hard shell to deal with, but the Akoya is a lot easier."
Once seeded, the shells are put into mesh panels, anchored in an undisclosed stretch of open water and cleaned every six weeks to ensure they get oxygen and nutrients.
"These are the first line to come from the hatchery," said assistant farm manager James MacFarlane, turning over a two-year-old shell.
"I've been here to see them grow from wee babies to getting them seeded and I'm sure I'll be here to get the pearl out of them."
Mr Humfrey's main business is land development and it has been his long-held dream to build a $27 million, 60-person eco-resort in the Abrolhos. Currently, only workers and their families and visitors are allowed to stay on the islands, but Mr Humfrey sees the A-class reserve as an untapped resource, particularly attractive to national and international tourists.
He was first given the go-ahead by the State Government to develop a resort on Long Island 10 years ago. He spent $3.5 million, including on environmental and visitor management plans, before the spectre of global warming and rising sea levels made the location unviable. Eight years later, authorities again gave Mr Humfrey the green light at the much bigger East Wallabi.
The island is covered in low scrub except for a gravel airstrip, jetty, public toilets and a shaded park bench, but Mr Humfrey has visions of solar-powered, low-rise chalets and a restaurant overlooking the beach.
"There are so many people who would love to come out here but you also need to control it," he said.
"There are so many boats coming out here now from Perth . . . but if you're going to give people access to the islands, you need to know where they're going, what they're doing and which islands they're coming into."
But Mr Humfrey said he would not move forward until the Government clarified its requirements, particularly for setting the resort back from the water.
The Department of Fisheries said it was working with Mr Humfrey and the departments of planning and transport on an indicative coastal setback to guide decisions on the site's location and design.