The first roller coaster at sea will feature on Carnival Cruise Line’s new ship Mardi Gras when it launches in 2020.

The line is promising that Bolt will run for almost 800 feet of twists, turns and drops with riders reaching speeds of nearly 40mph.

The electric roller coaster is to be built by a German company to allow two riders in a motorcycle-like vehicle to race along a track 187 feet above sea level.

Race car-like levels of acceleration are being claimed, with the track culminating in a hair-pin turn around the ship’s funnel.

Riders’ speeds are posted after the race, and passengers have their photo taken during the ride.

Mardi Gras will be based in Port Canaveral in Florida, with itinerary details to be revealed early in the new year.

Additional information on the ship’s “ground-breaking” features are due to emerge throughout the year.

A second XL-class ship will start construction in 2020 and be delivered in 2022 to mark the 50th anniversary of the founding of Carnival Cruise Line.

Company president Christine Duffy described Bolt as the cornerstone of innovations and features being designed for the vessel.

“Mardi Gras will be our most innovative ship ever with some truly special features and attractions, highlighted by Bolt, the first roller coaster at sea,” she said.

“Bolt will continue the tradition of Carnival providing exciting new ways for our guests to ‘Choose Fun.’

“We are so thrilled to introduce this one-of-a-kind, game-changing, exhilarating attraction – our guests are going to love it.”