Gladiator II introduces us to friends, Romans and sharks.

When “Gladiator” was released in 2000, fans and critics praised its visual effects and production design, from the towering colosseum to the detailed costumes and roaming tigers.

More than two decades later, the architects of that film have regrouped to take on a daunting task: build a sequel that captures what people loved about the first film's visuals, while finding new ways to surprise viewers as well.

“Gladiator 2” (in theaters Nov. 22) includes familiar elements — carefully choreographed sword fights and lofty speeches about the Roman Empire — but adds fight scenes in the Colosseum that involve rhinoceroses in one sequence and sharks in another.

“It's an epic film, more than an epic,” said Arthur Max, the production designer who worked with director Ridley Scott and producer Douglas Wick on both films. “Everything we did in the first film has been amplified to a much larger scale and scope.”

Much of the film's production design was based on meticulous research, with Max traveling to the Roman Ship Museum in Fiumicino, conservation laboratories in Pompeii, and museums in Athens, among other locations. They also examined models of warships at the British Museum in London and studied illustrations from military history books.

But the film also required some creative freedom, as many of the images and scenes were from Scott's imagination. Instead of using a computer, Scott imagined the scenes and then drew them for his team to recreate on screen.

“Even if I can’t find the location, I’ll visualize it and then draw it,” Scott said. “And then I’ll find a location that’s adequate for what I’ve drawn.”

“The most valuable thing I ever did in my life was go to art school,” he added.

One ambitious scene involves a clash in the flooded Colosseum. Two ships—one loaded with Roman soldiers, the other with gladiators—engage in a sea battle, circling and colliding with each other as sharks swim in the water below.

The ships were designed to be as lifelike as possible: They were 55 to 65 feet long, had real masts, wooden floors, iron spikes and tar plugs, Max said. The decks were made of wood and iron, with lightweight steel underneath.

Once assembled, they were moved by 120-foot cranes to two remote-controlled hydraulic vehicles, each with dozens of wheels. These movable platforms allowed the film crew to move the ships around the lot.

Aerial shots of the two ships were taken at the set of the Colosseum in Malta, where the original Gladiator was also filmed. These shots were shot on dry land, with water added later through visual effects.

“We decided it was more practical to do the water work in a drought because technology has advanced so much since the first film that it's now easier to put water in water than it is to work in water,” Max said.

To film the close-up scenes during this naval battle, in which gladiators and soldiers engage in hand-to-hand combat and some men fall into the shark-infested waters, the production team moved down the road to a giant tank, which was eight feet deep and about the size of a football field.

There, they built a section of the Colosseum, including water pipes in the shape of the head of Neptune, the Roman god of the sea. These pipes fed water into a reservoir, where a submersible pump recycled the water back into the pipes.

The idea of ​​introducing sharks into the water was Scott's. He got the idea from an incident that had happened years earlier, when he was filming “White Squall” (1996): while the director was staying at a hotel in the Caribbean, someone threw a six-foot shark into the pool, he said.

“They couldn't get him out, so the shark took over this pool on its own,” he said.

No one really knows if the Romans actually put sharks in the Colosseum, Max said, but the goal was to intensify the drama of the scene by showing these predators hiding in the water.

Scott also wanted to introduce other new animals into the gladiatorial battles, including a rhinoceros. To create the rhinoceros, the production team built a frame and covered it with synthetic skin, then mounted it on a smaller hydraulic vehicle, similar to those used on ships. Another scene features baboons, played by actors in black tracksuits and with their faces painted. They were given short crutches to mimic the creatures' forearms.

“The idea was to try to give the audience the same excitement that any Roman would have felt when watching the match in the stands,” Wick said.