When master Hawaiian feather worker Shad Kane received a commission to repair two royal standards, he didn’t know the job would spark a journey to a spiritual homeland. In order to recreate a historic pair of kāhili (feathered staffs), Kane ended up travelling to Midway Atoll, a tiny slip of land in the very centre of the Pacific.

Midway lies 2,100km northwest of the main Hawaiian Islands, within the Papahānaumokuākea National Marine Monument. On 26 August 2016, President Obama quadrupled the remote US monument, expanding it from 362,000sqkm to more than 1.5 million square kilometres – twice the size of Texas. It’s now the largest nature reserve on Earth. It’s also a feather worker’s paradise.

Kane specializes in kāhili, the tall staffs topped with resplendent feathers that accompanied royalty in ancient Hawai‘i. The two he was under instruction to clean originally belonged to Queen Liliuokalani, who ruled Hawaii until the monarchy ended in 1893, and were festooned with thousands of white albatross feathers, ebony frigate bird feathers and plumes from white- and red-tailed tropicbirds.

Unfortunately the feathers were too old to handle and disintegrated as soon as he started work. Kane agreed to create new kāhili using traditional methods and feathers from the same species, since Hawaiian ali‘i (royals) prized seabird feathers as symbols of strength and endurance.

“The birds that flew the longest distances and the highest elevations were considered to have the highest mana [spiritual power],” Kane explained. While ancient feather workers also made kāhili out of red and yellow feathers plucked from native forest birds, those were for the lesser ranking chiefs. “Migratory seabirds were reserved for the highest ranks.”

Kane first tried to collect the plumes at the few seabird-nesting sites in the main Hawaiian Islands, including the northwestern tip of O‘ahu and Kīlauea on Kaua‘i. It was a futile task; albatrosses are rare in the main Hawaiian Islands and there just weren’t enough birds. But millions of the majestic birds nest in the string of atolls and islets that make up the Papahānaumokuākea National Marine Monument. So Kane took a trip.

He and four colleagues, including a Native Hawaiian kahuna (priest), arrived on Midway Atoll in the dark of night.

“We went out in traditional dress to the eastern side of the island,” Kane said. “We performed chants associated with the rising of the sun.”

Very few people get the chance to visit Papahānaumokuākea. It’s uninhabited save for a few researchers. For Hawaiians, a visit to the distant marine sanctuary is nothing short of a spiritual experience.

This media cannot be played on your device.

The monument’s name, which is daunting for most people to pronounce, is a tribute to the cherished Hawaiian creation tale that describes how the Earth mother and sky father unite to create life.

“The name tells a story,” said Sol Kaho'ohalahala, a Native Hawaiian who helped choose the moniker when the monument was first designated in 2006. “It’s easy to say when you break it down. Papa is the Hawaiian Earth mother. Hanāu means birth, moku means island, and ākea is a contraction of Wākea, the sky father.”

According to ancient Hawaiian cosmology, Earth, sky, time and space blended to create the first living thing: a coral polyp. From that tiny genesis, all of life evolved. Native Hawaiians count corals among their first ancestors.

Papahānaumokuākea is a wonderland of diversity, home to rare corals, sea turtles, monk seals, sharks, and many endemic species yet to be discovered. Deep-sea explorations recently turned up a 4,500-year-old black coral – the planet’s oldest living creature – and an adorable, ghost-like octopus new to science that’s been nicknamed Casper. Every summer, pelagic birds descend on Papahānaumokuākea in noisy masses to mate and raise chicks.

“We were there in August, at the end of the breeding season. Most of the birds had already fledged. Even still, it was an extraordinary experience for us to see so many birds,” Kane said. “They were unafraid. They would let us come close.”

But the large number of dead birds dismayed him. “A lot of baby birds don’t make it for various reasons. Oftentimes, the parents pick up plastics in the ocean to feed to their chicks. And those birds eventually die.”

Even in death, the seabirds served a purpose. Over four days, Kane and his colleagues stripped dead albatrosses of their feathers. “We’d start around 8:30am and work until 3pm. The kahuna was chanting for the entire time. He wanted to make sure it was done in traditional fashion.”

Kane retrieved enough feathers to fill five large boxes to take home. Back in his workshop, he painstakingly attached more than 24,000 feathers to two 16ft-tall staffs. Each staff took six to eight weeks, and they were so well received that he created another two to decorate the throne chamber in ‘Iolani Palace.

But for Kane, the visit to Midway was not only a wonder but a wake-up call, too. “What amazed me most was the amount of fishing trash on the island: buoys, nets, all kinds of floating trash.”

The feather artist was inspired to join politician Sol Kaho‘ohalahala on the Papahānaumokuākea Native Hawaiian Cultural Working Group, which advises the monument’s management team. Kane and Kaho‘ohalahala were among the thousands of Native Hawaiians, conservationists and politicians who urged President Obama to expand the monument and further safeguard its natural and cultural treasures.

“It’s something that clearly needed to be done,” Kaho‘ohalala said. “We need to allow future generations to experience the gifts and resources of this place.”

If you liked this story, sign up for the weekly bbc.com features newsletter, called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Earth, Culture, Capital, Travel and Autos, delivered to your inbox every Friday.