Dublin City Council has already spent more than €500,000 developing its plans for a white water centre at George's Dock in the IFSC.
The local authority wants to turn the dock adjacent to the CHQ building into a paddle sports facility, along with an emergency service training centre.
Figures released to RTÉ's Prime Time show the council has spent €565,000 on the proposals, including sending two members of Dublin Fire Brigade to Syracuse, New York, where there is a similar water rescue training centre.
The trip in May 2018 cost €3,530.
Earlier this year, a Dublin City Council official also travelled to London and Cardiff as part of the project.
The local authority said €8m will come from grants that have not yet been awarded.
The remaining costs will come from local development levies and a further €8m from council reserves and borrowing.
Canoeing Ireland, which has 4,500 members, has welcomed the council decision.
Six-time national K1 kayak slalom champion Samuel Curtis, said it would be a "game changer" for his Olympic ambitions.
"I would be able to train at an international level in Ireland all year round. Currently, I often train out of the boot of a car."
The 25 year-old, who frequently travels overseas to train, said critics of the cost of the facility needed to consider "not the expense but the investment".
"If we have this facility it will increase participation and performance in the sport."
However, at a protest at Leinster House against the planned closure of the Markievicz public swimming pool, there was little enthusiasm for the white water plans.
Demonstrators posed for photos in an inflatable paddling pool with signs reading "Save our Pool".
The facility is being closed to make way for the underground Metrolink.
John Dean of the Save Markievicz Pool and Gym group said the council was not taking the community seriously.
He said: "There was €1.5m put into the Markievicz pool a few years ago and now they want to abolish it.
"At the same time they are talking about spending €22m on a white water rafting facilty. It just doesn't make sense."
Demonstrator Lyndie Farmer said she could not see the logic of the white water centre.
"I haven't heard an argument for it apart from the fact some city in the world has made a few bob out of it," she said.
Another protester, Mona Deering, described the facility as a "waste of bloody money".