The proposals for Lagoon Hull have been five years in the making, but are only now being revealed following extensive feasibility studies.
The plan would see an 11km southern relief road built from Hessle to Hull docks and behind it a lagoon, forming an attractive new destination for waterfront living.
A new outer harbour and port facilities, is also envisaged, creating 14,000 jobs through the western dock’s regeneration.
The lagoon would make waterfront living a reality - “cafe culture on a massive scale” - and could see long derelict sites at St Andrews Quay finally realise their potential.
“This is reinvention of many ideas over the years,” said Tim Rix, managing director of fifth-generation family firm J R Rix & Sons Ltd, whose brainchild it was.
“People have talked about a road on stilts or having a bund - we have combined everything and done the homework to say why it would work.”
The sceptics were defied by Hull getting the Siemens wind turbine factory and then hosting City of Culture in 2017 - and after 40 years of industrial decline a cool £3.5 billion has flowed into the area in past five years.
Mr Rix thinks Lagoon Hull will take the city from appearing on the weather map to the world map - if not immediately.
It could take another five to 10 years of technical studies and consenting, with the actual build taking five years.
Paul Hatley, who had worked as chief engineer for Associated British Ports, was tasked with testing the feasibility of the idea - from examining the river’s morphology, to the environment and the impact on flooding.
Having spent three years trying to find every reason why it could not be done, he concluded: “Remarkably at every turn the answer says: yes it can be.”
Highways England is about to start work on the long-awaited £392.5 million scheme to improve Castle Street in Hull, partly to ease congestion to the port.
But Mr Hatley said “what is very clear is as soon as you’ve done Castle Street, we need to do something more - it’s just not enough.”
On the environment - the estuary has multiple layers of legal protection - Mr Hatley believes there are opportunities for habitat creation at either end of the scheme, and along the causeway.
He said: “I’ve worked with the environment team at the University and they have looked at this at high level, and their views are that the impact of this aren’t going to be as severe as the scale of the project would suggest. They feel it is really worth trying for, bearing in mind the scale of the benefits it brings back to society.”
Two independent bodies have looked at how Lagoon Hull would impact flooding, marine consultancy ABPmer ,which has been modelling the Humber for 30 years, and the University of Hull.
“We had two independent authorities using different models and data and both came to exactly the same conclusion,” said Mr Hatley.
“If you build the lagoon, water levels in the river seem to go down, rather than up, which flies in the face of the traditional coast squeeze argument.”
Economic studies have also predicted the project - which has the support of city MPs - could add £1 billion gross value added to the region’s economy annually.
A launch event is being held in Hull on Friday as the not-for-profit company chaired by Mr Rix, seeks support for further feasibility work.
Mr Rix said: “It addresses the key challenges of today and unlocks our region’s potential for future economic growth, for placemaking and creating a city and region where not only young people will want to stay and live, but that attracts new and talented people to live and work.”
Support has come from the city's three MPs, including Emma Hardy, who said: "What we need now is for people to get behind it and support it so we can turn this amazing ambitious project into a reality."
Lord Haskins, chairman of the Humber Local Enterprise Partnership, added: "The Lagoon Hull would not just set the scene for the next century of investment and development in the region, it would make Hull one of the most exciting waterfront cities in Europe, possibly even the world."