The global increase in wealth has caused at least one sector of the luxury market to expand in size: yachts.

And when industry officials say the industry is expanding, they’re speaking literally.

It used to be that a “big” yacht was considered to be in the neighborhood of 150 feet, but over the past five years, with buyers having money to spend on convenience and glitz, it’s not unusual to see christenings of “super yachts” that exceed 250 feet or, in some exceptional cases, 500 feet.

“Yachts are getting more luxurious and becoming expressions of the owner’s personality,” said Robert van Tol, operational director with Super Yacht Builders Association (SYBAss). “What in the past was an amenity is nowadays almost standard.”

Super yachts can carry anything from luxury cars to helicopters, but things can get even more extravagant than that, industry officials said.

The 590-foot Azzam, for example, is reportedly the largest yacht in the world. Owned by United Arab Emirates President Sheikh Khalifa bin Zayed Al Nahyan, it carries a submarine and its own missile defense system.

The ship also is outfitted with “anti-paparazzi lights” on multiple decks that are designed to guard against photographers.  One set costs about $15,000, including installation. Some 10 to 15 light sets are needed to be effective depending on the yacht.

“The super-rich don’t want to necessarily be visible to news photographers,” said Luc Khaldoun, head of client advisory for OneOcean Ventures, a yacht consultancy based in the U.K. “When you flash anti-paparazzi lights from a yacht, it’s impossible for photographers to get a clear shot, even with high-end equipment.”

Although the Azzam is an anomaly in terms of its capabilities, yachts over 250 feet are growing more common, including some that include sports fishing vessels that travel alongside them.

“Russian entrepreneurs started the super-yacht trend, but now I see clients from Central America, the U.S. and the Middle East, which has always been a market that buys large yachts,” Khaldoun told Private Wealth.

Some 300 super yachts were sold in 2015, according to BoatInternational.com, with $215 million the highest price paid. The largest sold this year was a 456-foot vessel.

One of the reasons yachts are getting bigger is because buyers are asking for vessels that include land and air vehicles, Khaldoun said.

At the annual Fort Lauderdale International Boat Show in Florida, for example, there's been an increase in demand for yachts equipped with helicopters and helipads.

"Carrying a helicopter gives yacht owners the ability to get to shore faster than a tender and passengers use the helicopter for sightseeing once they are docked,” said Danielle Butler, president of the Marine Industries Association of South Florida and managing partner of the Luxury Law Group.

Both the Bell 407GXP and Bell 429 helicopter are a popular aircraft for yacht owners. Priced at $3 million, the Bell 407 has limousine-like seating for six people, while the Bell 429, priced at $6.5 million, carries seven passengers and has a greater cruising range.

“Passengers can fly directly from their home or the city center to their yacht, eliminating the need to drive to shore and transfer to a boat,” said Charles Evans, director of marketing and sales support with Bell Helicopter in Fort Worth, Texas.

However, traveling by helicopter in between marinas has not completely replaced the use of tenders. In fact, the ultra-rich are now incorporating multiple tenders in addition to helicopter travel.

They may have one tender on board to transport guests from sea to shore for a night on the town, which can be outfitted like a limousine, with a minibar, sound system, TV set, leather seats and air conditioning.

A second more functional tender can used to transport supplies, staff and crew, while a third tender can be used for water sports, industry officials said.

“Ten years ago, tenders were rubber dinghies, but now they are just as gorgeous as the super yacht, but smaller in size,” Butler told Private Wealth.

Millennial yacht enthusiasts are trending towards builders who can offer them environmentally friendly vessels, they said.

“All of the yacht builders are moving towards manufacturing a greener yacht to reduce black or grey water implications, to lower gas emissions and reduce their carbon foot prints,” said Butler. “They are aiming for an environmental footprint that’s as minimal as humanly possible because younger buyers are demanding it.”