Le Nordik says it is spending $4.1 million on the expansion, which is scheduled to be completed in July and create approximately 15 new jobs.
Among the new amenities is a new 1,200-square-foot pool - large enough for 35 people - containing a high concentration of magnesium and sulfate salts that allow users to float on the surface.
Co-owner Daniel Gingras said in a statement that the expansion was driven by the "increasing demand" among clients for new experiences.
When completed, Le Nordik says it will have 41,500 square feet of interior space and 80,000 square feet outside.
The company received financial assistance for the expansion from Quebec's Ministry of Tourism.
Late last year, Le Nordik announced plans to expand to Manitoba and construct a $6.5-million facility in Winnipeg.