This is HMS Queen Elizabeth, making its first voyage as an official member of the Royal Navy. Tugboats steered her past the Round Tower which guards the mouth of Portsmouth Harbour. At 56m tall, the carrier dwarfed it.
The carrier has sailed before, but only joined the navy for keeps in December, when it was commissioned by Queen Elizabeth II in a grand ceremony.
The highlight was an enormous cake shaped exactly like the ship.
The stern of the ship flew Britain's Naval Ensign, a flag used by military ships at sea.
With the Ensign flying high we say goodbye. #QNLZAtSea pic.twitter.com/LhaeB0cO42
— HMS Queen Elizabeth (@HMSQnlz) February 2, 2018
And the Royal Navy uploaded social media video of the carrier in transit.
Watch HMS Queen Elizabeth @HMSQnlz sail from Portsmouth today as she heads to sea for her first helicopter flying trials. #QNLZAtSea pic.twitter.com/54kwP6mgVR
— Royal Navy (@RoyalNavy) February 2, 2018
Ahead of the departure, two twin-engine Chinook transporter helicopters landed on board, and will take part in the trials.
Here's how the Royal Navy described the purpose of the exercise:
"The aim of the trials is to work out the conditions that the aircraft can operate in while at sea on the carrier.
"They will collect data about the landings, take-offs and manoeuvres in different wind and sea conditions, before processing the information and ultimately declaring that the ship can safely operate the aircraft."
Here's another view of the choppers.
Chinooks are a mainstay of British air power, and have been in service since 1980.
The 30 metre-long tandem helicopters can carry around 55 people, or 10 tonnes of freight, and fly at around 180mph.
They are not combat craft, but can be equipped with two miniguns and a machine gun.
A few days after, Merlin helicopters flew out to join in, dispatched from Culdrose Royal Naval Air Station in Cornwall.
Merlins are a medium-sized transport helicopter. They can carry around 30 troops each and fly at speeds in excess of 190mph.
Britain's newest aircraft carrier has set sail on its first mission with helicopters - here are all the pictures
As well as carrying people, they can also carry weapons, such as torpedos and depth charges.
They can also act as scouts, thanks to advanced sensor systems on-board. Each one can scan the seas and send information back to the Queen Elizabeth from hundreds of miles away.
Eventually, 14 Merlins will be stationed on the Queen Elizabeth full-time.
The Queen Elizabeth is the first "twin-island" aircraft carrier in the world. Most carriers have one tower on deck to steer the ship and handle the aircraft, but the Queen Elizabeth split the tasks. They tweeted a view of the assembled helicopters for the read tower, used for flight.
A day of aircraft movements with 820 Sqn. from @RNASCuldrose has kept our Air Traffic Controllers in flyco busy. #QNLZAtSea pic.twitter.com/8O90nFgdyw
— HMS Queen Elizabeth (@HMSQnlz) February 5, 2018
Eventually HMS Queen Elizabeth ship will carry F-35B Lightning fighter jets, which will launch from its ski jump-style ramp. Here are the planes practising in at an air base in the US.
Here's an F-35B in action — this one belongs to the US Marine Corps and was testing munitions over the California desert.
In the future, the Queen Elizabeth could also be a platform for drones. Here's a Northrop Grumman X-47B combat drone on the flight deck of American carrier USS George Bush.
Captain Jerry Kyd, the commanding officer of HMS Queen Elizabeth, told Business Insider in an interview last year that "it's an absolute inevitability that [drones are] going to be embarked on this ship in the near future."
The carrier was last seen off the coast of Cornwall, the southwestern tip of the UK. This photo was taken by a local newspaper photographer, showing the ship near the St Michael's Mount landmark.
Penlee lifeboat looked tiny as it approached HMS Queen Elizabeth in Mount's Bay today. The UK's largest ever warship even made the enormous St Michael's Mount look small. https://t.co/umGr5tX9Yx @ntmichaelsmount @CornwallLive @penleelifeboat @HMSQnlz pic.twitter.com/FQS7vbgTHM
— Greg Martin (@photogregmartin) February 5, 2018