A scientific research ship the public wanted to call Boaty McBoatface will be formally named after Sir David Attenborough.
The Duke and Duchess of Cambridge toured the RRS Sir David Attenborough on Thursday at the Cammell Laird shipyard in Birkenhead, Merseyside, alongside the naturalist to see the state-of-the-art equipment on the ship's flight deck.
Sir David hailed the "astonishing" ship and told the visiting crowd.
He said it is "no news" that the world is facing "great, great problems" and that the most aware of that are today's young people.
"There could be no more important function for any ship, anywhere in the world than those which are going to be dealt with by this remarkable ship at the cutting edge of science," he added.
"It is the greatest possible honour that this marvellous ship should carry my name."
Speaking before the naming ceremony, William said: "As last week's climate protests the world over and yesterday's report on our oceans and frozen regions demonstrated, there has never been a more important moment for this ship to get to work, and there is no person more fitting for this beacon of scientific research to be named after than you, David.
"You have shown us how awe-inspiring the natural world is, and also how fragile and endangered it is, and you have inspired us all to do as much as we possibly can to protect it.
"It is my immense privilege and relief to welcome Sir David Attenborough, rather than Boaty McBoatface, to speak."
Kate, the ship's sponsor, formally named the vessel and a bottle of champagne was smashed against the hull to mark the occasion.
The duke and duchess were given a tour of the ship and met engineers, including young apprentices, who were involved in the build.
They also met scientists, schoolchildren and heard from the ship's captains and crew members about its ice-breaking capabilities and navigation systems.
Mackenzie Grieman, an ice core scientist with the British Antarctic Survey (BAS), and colleague Rob Mulvaney showed the royals ice core which is 85,000 years old.
What will the ship be used for?
The RRS Sir David Attenborough, which cost around £200 million to build, is set to act as a "floating research fleet", allowing scientists to study the world's oceans and understand more about climate change.
It was commissioned by the Natural Environment Research Council (NERC), built by shipbuilding company Cammell Laird to a Rolls-Royce design, and will be operated by the British Antarctic Survey (BAS).
Housing state-of-the-art equipment, the ship will be available to the UK research community and allow scientists to remotely deploy robotic instruments to areas humans cannot access.
Why is it needed?
The vessel is set to replace two other polar research ships: The RRS James Clark Ross, which is nearing the end of its 25-year lifespan, and the RRS Ernest Shackleton, which was returned to its owners GC Rieber this year after 20 years of service.
The ship, according to BAS, has better fuel efficiency compared to its older counterparts and is expected to save more than #100 million in operating costs over its 30-year lifespan.
It will operate in both Antarctica and the Arctic and will be able to endure up to 60 days in sea ice without being refuelled.
What are its features?
Weighing around 10,400 tonnes - that is 1,400 elephants combined - the research ship hosts a wide range of specialist scientific equipment that will allow researchers to study the ocean, seafloor and atmosphere.
Robotic submarines and marine gliders will gather information on ocean conditions and marine life for scientists working in the ship's on-board laboratories, while airborne robots and environmental monitoring systems will provide data on the surrounding environment.
Other features include an ice-strengthened hull designed to break through ice up to one metre thick, and a "moon pool" - a 4m by 4m vertical shaft running through the vessel that allows instruments to be deployed through an opening in the hull rather than over the side.
Measuring 129m long, it is made up of one million pieces of steel and has 30km (18.6 miles) of piping and 750km (466 miles) of electrical and data cables.
The ship has beds for up to 30 crew and 60 scientists and support staff.It will also be able to deploy and recover large remotely-operated marine vehicles.
So what happened to Boaty McBoatface?
Despite topping a public poll in 2016, the name was vetoed as the moniker for the polar research ship.
Initially suggested as a joke by a voter, Boaty was the out-and-out favourite, amassing more than 124,000 votes in a poll conducted by NERC.
Jo Johnson, who was science minister at the time, said the suggestions for the name of the vessel had "captured the imaginations", but added that Boaty McBoatface would instead explore the polar seas as a yellow submarine.
The minisub has since performed its first mission, investigating water flow and turbulence in the dark depths of the Orkney Passage, a 2.17 mile-deep region of the Southern Ocean.
Boaty will continue its scientific missions in the polar regions alongside RRS Sir David Attenborough.