A $300 million super yacht with a stairwell banister worth $60,000 and bath knobs costing $40,000 each has berthed at Honolulu Harbor.

Norman Cheu, owner of Norko Marine Agency, said the boat, whose arching hull reminds him of a submarine, is the most impressive vessel he’s seen in 30 years as a ship agent in Hawaii.

"I was awestruck with the design," said Cheu, who boarded the vessel, called "A," after it arrived at Pier 11 in Honolulu Harbor on May 23. "There was a number of people, state employees actually, standing on the pier watching them come in."

Cheu, whose company is representing the boat while it is in Hawaii, and immigration officials boarded the vessel by a gangway and were ushered into a room to process those onboard in about one hour.

"During that time we were just working," he said by phone. "Basically, it was just to take care of business."

Cheu didn’t get a tour of the boat and never met its owner, Russian billionaire Andrey Melnichenko, 42, who amassed his wealth in energy and fertilizer. He said to protect his client’s privacy he couldn’t say whether the owner is onboard.

Melnichenko named his yacht A after himself and his wife, supermodel Aleksandra Nikolic.

The state Department of Transportation said the 394-foot A is taking up two piers, a cruise ship terminal and an all-purpose pier. The department said the vessel’s owner is paying rent for both piers.

The department couldn’t immediately provide the vessel’s cost to berth in Honolulu Harbor.

Cheu declined to say where the yacht had come from and where it will head to next. He said he didn’t know when it will depart.

Designed by Philippe Starck of France, Motor Yacht A was launched in 2008 from a shipyard in Kiel, Germany. Its port of registry is Hamilton, Bermuda, and it has a crew of 37.

According to the Wall Street Journal, it has 24,000 square feet of interior space, including a 2,500-square-foot master suite surrounded by bombproof glass. Six guest staterooms have movable walls so they can be configured into four larger suites.

Living space on A, which can accommodate 14 guests, is therefore at least 23 times larger than an average two-bedroom apartment in Honolulu.

The interior design is dominated by mirrored surfaces, Baccarat crystal and animal hides.

There are a helipad and a swimming pool on the forward deck, and two more pools toward the stern, one of which has a glass bottom and can be viewed from the below-deck entry hall/discotheque.

Cheu said his company, which represents a variety of maritime vessels docking around the islands, arranges services for the vessels while they are docked. He said that no work has been scheduled for the A while in Hawaii.

Chronicles of the boat drew a few onlookers to the pier.

Blake Blackman of Honolulu pulled into a parking lot along Nimitz Highway to take photos of the luxurious vessel with her friends.

"It’s beautiful," she said, but added that it wasn’t as lavish as she expected. "This one doesn’t really blow my mind for it to be that expensive."

Bought for $323 million, A is the fifth most expensive luxury purchase of all time, according to research firm Wealth-X.

On the same list, published in December, Larry Ellison’s $500 million purchase of Lanai in 2013 ranked second. In first place was Azzam, the world’s largest private yacht at 590 feet long, delivered in 2013 to United Arab Emirates President Khalifa bin Zayed Al Nahyan for $627 million.

But A didn’t break the bank for Melnichenko, who has a current net worth of $12 billion, according to Forbes.

A also has twin high-speed diesel engines that deliver 24,000 horsepower and can move the boat about 27 mph. Fueling the mega-yacht costs more than $500,000, according to the Wall Street Journal.

According to a 2010 Wall Street Journal article, Melnichenko spends weeks at a time at sea. He spent several months in the Mediterranean in 2009. In 2010 it was the Caribbean.

Cheu said this is the first time that A has visited Hawaii.

For a video tour, go to the Wall Street Journal at on.wsj.com/1kPwKa4.