Britain's new polar ship, the Sir David Attenborough, has left her Merseyside construction yard.
Sirens and accompanying tugboats marked the Attenborough's departure from builder Cammell Laird's wet dock at Birkenhead.
Four years in the making, the £200m vessel is about to venture out on a series of sea trials.
But her first journey was only a short one - a few hundred metres down-river to Liverpool's cruise terminal.
She's going to be tied up there for a few days of final crew training and familiarisation, before then heading off into the Irish Sea.
The Attenborough is going to sail across the north Wales coast to Holyhead, which will be her base for the next year. But she can't arrive until after the latest Welsh Covid lockdown, which ends on Monday 9 November.
"This vessel is a true celebration of British expertise - from the team who built it right through to the scientific community that will call this ship home," the company's David McGinley said. "The RRS Sir David Attenborough is the single biggest and most ambitious build in the history of Cammell Laird and it's an incredibly proud moment to see her embark on sea trials."
Engineers need to run the rule over all the vessel's systems and equipment before it can be released to support UK scientists in the Arctic and the Antarctic.
These trials will include an assessment of the Attenborough's ice-breaking capabilities.
The design specifications called for a ship that could crunch through frozen floes with a thickness of up to 1m and at a speed of 3 knots (1.5m/s).
If all goes well with the tests, the Attenborough will make her first cruise to the Antarctic in November 2021.
Prof Jane Francis, the director of the British Antarctic Survey (BAS), said the new vessel represented a huge investment in the science of climate change.
"We've all heard about how the Arctic sea-ice is melting very fast, but the great ice sheets, such as Antarctica, are also melting in a warming world. The RRS Sir David Attenborough is going to allow us to get right up to the edge of the ice sheets, to deploy its new technologies, to really understand what's going on," she told BBC News.
BAS will operate the ship on behalf of its funding agency - the Natural Environment Research Council (Nerc).
The 129m-long, 15,000-tonne Attenborough is the largest commercial ship built in Britain in three decades.
Her initial keel block was laid in October 2016, with the 10,000-tonne completed hull section entering the River Mersey in July 2018.
Since then, Cammell Laird has been installing all the fixtures and fittings, and undertaking a 60,000-litre paint job inside and out.
The yard's Claire Wainwright, who managed the outfitting, said of the ship: "I think aside from my daughter, she's one of my biggest achievements. Knowing what she's heading out there to do."
And likewise, Cammell Laird apprentice Callum Kerr said: "Four years… and to look at it now, under its own steam and in the Mersey. It's great to see."
But while the Attenborough's many systems can be, and have been, tested in wet dock, the ship's readiness for service won't be signed off until she's been through deep-water trials.
"What we'll be doing is going out on what are yard sea trials initially and that will involve the yard as the vessel owner effectively doing all their tests," explained BAS ship captain Ralph Stevens.
"And then we'll take the ship to Holyhead where we'll take ownership of the vessel. And that's when it really starts for us. We've got a year of trials ahead of us."
The Attenborough is a state-of-the-art polar research ship.
She has a helipad (helicopters are essential for exploration and safety), cranes and onboard labs, and she has an enhanced ability to deploy subs and other ocean-survey and sampling equipment.
One of her key features is an enclosed "moon pool".
"This is basically a hole in the ship that goes all the way down to the surface of the ocean, through which you can deploy different instruments, whether that's a biological net, or something to sample the ocean water," BAS marine geophysicist Dr Kelly Hogan told BBC News.
Colleague Dr Rob Larter is excited by the sediment-coring capabilities offered by the Attenborough.
The muds around Antarctica retain a record of its past climate, and the new ship will be able to investigate this history over longer time periods and in more detail.
"The Attenborough will be equipped with a giant piston corer capable of collecting cores over 40m long," Dr Larter said.
"This became an option because the size of the ship makes it possible to deploy and recover such a long core barrel length over the starboard side of the ship between the stern and the midships A-frame."
The longest corer barrel length that can be deployed on BAS's existing polar ship, the RRS James Clark Ross, is just 16m.
The Attenborough came to the public's attention, of course, in an online initiative in which the public was asked to suggest a name.
"Boaty McBoatface" was the suggestion that garnered most support.
Ministers, however, rejected this as inappropriate, and ordered that one of the country's most recognisable TV personalities, with a lifetime's association with the natural world, be honoured instead.
In a move that is sure to be appreciated by all who sail on the ship, it's been announced that Sir David has recorded the regular onboard announcements.
"Your attention please," says the familiar voice. "Any personnel not sailing with the vessel, please disembark - as the vessel is about to proceed to sea."