The research ship which members of the public voted in favour of calling Boaty McBoatface has been launched into the River Mersey in Birkenhead.
RRS Sir David Attenborough, named after the famed broadcaster and naturalist, will be used for climate and ocean research in Antarctica and the Arctic.
Speaking at the launch, Sir Attenborough said seeing his name on the side was "the greatest possible honour".
The £200m vessel became famous two years ago when radio host James Hand suggested it should be called Boaty McBoatface.
It became an online sensation and won a public vote with over 120,000 votes cast for the name, but the Natural Environment Research Council (NERC) had the final say and overrode the public’s decision.
Hand ‘apologised profusely’ to the organisation for the internet campaign.
About 2,000 members of the shipyard and invited guests from the worlds of science, technology and engineering attended the event on the slipway at Cammell Laird.
"Our future and everybody's future will be affected by what people on this ship will be discovering for years to come," Sir David said.
"The Antarctic, far from being remote and desolate, is key to understanding what is happening in the entire globe and what is happening here."
The research ship will replace the two in the UK’s existing polar fleet – the RRS James Clark Ross and the RRS Ernest Shackleton – which were both launched in the 1990s. It is the largest civilian ship to be built in the UK for 30 years, according to the British Antarctic Survey.
The 10,000-tonne hull of the vessel was launched on the River Mersey at 12.25pm, after which it was towed away for the next stages of construction. The ship is scheduled to come into use in 2019.
"We'll take her up into the Arctic and test her performance in the floes and that will give us a really good yardstick to know how far we can push this vessel. Her first year, 2019, is really a rehearsal year when we test everything onboard. In 2020, she'll be fully operational," Captain Ralph Stevens from the British Antarctic Survey told BBC News.
The ‘state-of-the-art’ ship is designed for near-silent running when required, allowing scientists to study sea creatures without disturbing them
Although the NERC rejected the public's suggestion for the name of the ship, it announced Boaty McBoatface would live on after the vote, as the name of a submersible vehicle which will be deployed from it.
Agencies contributed to this report
