And then, there are the really big boats.

This is a cruise ship: The MSC Meraviglia.

Built in Saint-Nazaire, France, in service since 2017, and christened by Sophia Loren.

It is the— [ship honks]

Sorry, she is the biggest cruise ship to have ever docked in New York City.

There's a water park, a rope course, a spa, a mall, an arcade, a bowling alley, a casino, a gym, two theaters, five pools, nine restaurants, 23 bars, 19 floors,

and enough room for 5,655 passengers and 1,536 crew members.

Cruise ships are the biggest passenger vessels that humans have ever built.

They can fit a small town's worth of people into a single vehicle but they have a certain look to them, far from the look of the big transatlantic ships of 100 years ago.

So how did the biggest ships we build wind up looking like this?

Before cruise ships, the biggest ships on earth were ocean liners.

Built for one purpose: To take you somewhere.

In the golden days of ocean travel before the airplane, people had no choice. They had to use ships.

That's Peter Knego.

He's a cruise journalist and ocean liner historian.

Advertisements from this golden era of ocean liners boasted their speed across the Atlantic and their luxurious comfort, which given the conditions on the open ocean, wasn't always easy to achieve.

If it's February and you're crossing the Atlantic, you're going to be absolutely miserable.

And the last thing you want to do is realize that you're on a ship.

What they used to do at the turn of the 20th century (was that) they would design, at least for the first-class part of ships, to look like great palatial hotels or even palaces themselves.

Ocean liners like this one, the RMS Aquitania tried to replicate all the amenities of life on land.

There were restaurants, smoking rooms, gardens and a massive lounge with painted ceilings.

For the first-class passengers, at least, all of the comforts of a city but at sea.

There was a picture of the Aquitania lined up against what was then the world's tallest building: The Woolworth Building.

And the Aquitania was longer and taller than the Woolworth Building.

And that was their way of saying this is like literally a floating city at sea.

Just to inspire the confidence of passengers.

But the rise of air travel meant that ships stopped being being the only way to cross oceans.

And by the 1960s, ocean liners were slowly becoming obsolete.

As ocean liner companies struggled to sell tickets, they tried something different.

"No longer do liners even attempt to compete with air speed."

Now the word is luxury."

"A vacation at sea."

They continued transatlantic service in the northern Hemisphere's summer months.

But in the winter months, more companies started offering leisure trips to warmer regions.

And they started advertising ocean travel differently.

From selling transportation to selling a vacation.

The cruise ship was born.

But they got off to a slow start.

They didn't really take off until the TV show The Love Boat, which exploded the idea of cruising.

It wasn't just something that your rich grandmother did and made cruising something for the mainstream.

But as cruises started to become mainstream, ocean liners had a problem.

They were designed to go fast and consumed a lot of fuel.

They sat low in the water, which kept them stable in rough seas, but meant they could only access ports with deep harbors.

They had separate sections for first, second, and third class, but that left a lot of passengers without access to amenities, and limited everyone's freedom of movement throughout the ship.

And compared to the full time cruise ships of the time, ocean liners were huge.

So they'd have to attract a lot of vacationers to be profitable.

Everything that had made ocean liners optimally designed for commuting quickly through rough waters made them poorly fit for vacationing slowly through calm one.

As sea travel continued to dwindle, even the largest ocean liner in the world, the SS France, couldn't generate enough revenue to operate.

And it sat idle for years until 1979 when Norwegian Caribbean Lines purchased it and made an announcement that shocked the industry.

They were going to convert the France into a full time cruise ship.

Since speed was no longer a concern, they shut down one engine room and removed two of the four propellers.

To get passengers to islands without deep ports, they installed tenders.

These are smaller ships that ferry passengers to shore.

To open up amenities to all passengers, they took out the barriers between class sections.

And to attract enough vacationers, they loaded the ship with a massive roster of entertainment options.

There are sporting facilities and shopping centers, cinema, bars, a multi-confession church, saunas, kindergarten, party games, educational courses, library, charades.

The ship began service in 1980, renamed the SS Norway.

Where other ships made 3 to 4 stops in a weeklong cruise, the Norway only made two.

They weren't advertising a cruise to a destination.

The ship was the destination itself.

The Norway proved that size worked for cruise ships and it kicked off a race to build bigger and bigger ships that changed the look of cruise ships forever.

To fit more cabins and amenities, those superstructures that's all of this that rises above the deck, became taller which hid the once prominent smokestacks.

The smokestacks, because the ships are so tall, the funnels are these tiny little afterthoughts.

To fit even more cabins and amenities, superstructures became wider, which shortened the bow.

That's this forward part of the ship.

There is no space where there's just an open deck where Jack and Rose can go stand and say they're king of the world or whatever.

That's all gone.

The bow didn't need to be long and pointed to cut through intense waves like on transatlantic liners.

So builders rounded them out, giving even more square footage for amenities.

When the Norway began service in 1980, it was the biggest operating passenger ship in the world.

With an internal volume of over 70,000 gross tons.

But the ships built over the following decades make the Norway look tiny.

And even make once legendary ocean liners look small.

The ship that held the record for so many years was the Queen Elizabeth of 1940.

She was 83,000 tons.

People said they will never build a ship that big again.

Well, now the new Royal Caribbean ships are literally three times the size.

When this ship, the Icon of the Seas, launches in 2024, it'll be all the way up here with a volume of over 250,000 gross tons.

That elegance of design is missing.

I think, on a lot of the big new ships.

It's just the way things go.

And, you know, we all miss what came before and pine on.

And I'm sure people in 50 or 100 years from now will pine on about how great-looking the ships were back in the 2020s.

There are over 320 cruise ships sailing around the world right now, but there's only one ocean liner left.

The Queen Mary 2; also built in Saint-Nazaire, France in service since 2004 and christened by Elizabeth II.

Still in regular service from Southampton to New York City.