Therme Group has unveiled a second major redesign for the Therme Spa at Ontario Place, cutting the building’s footprint to about half of the intial plan, and further expanding public access across the West Island. Now planned at 33,000m², down from the original 65,000m², the update follows requests from Toronto City staff to scale back the development after concerns were raised about the size and dominance of the previous designs.

Looking southwest to the updated design for the West Island, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

The revised plans come amidst months of public controversy and planning scrutiny surrounding the project, which has been at the centre of debate since first unveiled. City staff raised concerns in August, 2023 that the previous plan overwhelmed the natural landscape of the West Island, encroached on heritage elements, and left insufficient space for public use. 

Looking west to the previous design by Diamond Schmitt Architects and STUDIO tla for Therme Group

The updated spa, designed by Diamond Schmitt Architects, would now consist of two main buildings rising seven (26.3m) and nine (45.15m) storeys. The total built area has been reduced, in part achieved by separating out the parking structure, which had previously contributed to the overall massing. The revised layout adopts a campus-style arrangement, distributing program areas across several smaller interconnected volumes rather than one continuous block. 

Water slides at Therme Spa, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

Inside, the design is organized into three experiential zones: Play, Relax, and Restore. The Play zone includes a wave pool and more than 20 water slides, one of which weaves in and out of the building envelope. The Relax and Restore areas feature a mix of mineral pools, cold plunges, and wellness amenities such as 14 saunas, 9 steam rooms, and an ice fountain. Dining and lounge spaces are distributed throughout, along with flexible programming that ranges from family-focused daytime activities to nightlife-style events on weekends.

An aerial view of the three zones, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

Surrounding the spa, 16 acres of public parkland are planned for the West Island. The new design includes three outdoor swimming areas: a sandy beach, a lake-access pier, and stepped entry points along the shoreline. A public trail would encircle the spa and extend across the site, connecting with the Martin Goodman Trail and the East Island. Public amenities such as year-round showers and changerooms are included, alongside rooftop green space and waterfront landscaping.

Public trail along the water edge, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

For circulation, a multi-use trail would loop around and over the spa buildings, linking to existing infrastructure like the Martin Goodman Trail and providing continuous access between the West and East Islands. The perimeter trail, green roof, and lakefront pathways would remain publicly accessible at all times, as part of the project’s commitment to maintaining open, unticketed parkland. Elevated sections of the route are to connect to the architecture, offering views over the water and into the spa’s interior zones.

Wave pool at Therme Spa, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

In addition to circulation upgrades, the plan also introduces two new pavilions as venues for cultural programming, designed to accommodate festivals such as Luminato and Nuit Blanche. Indigenous design elements are incorporated throughout, including a constellation-aligned roof feature inspired by the “Wintermaker” stars. 

Previous master plan and design for the West Island by Infrastructure Ontario

While Therme’s lease permits limited commercial activity across 30% of the public realm, company representatives stress that this is intended only to support free public events (such as food vendors or equipment rentals), not private or ticketed zones. The lease explicitly requires the park to remain open and freely accessible at all times.

Rooftop infinity pool at Therme Spa, designed by Diamond Schmitt Architects and STUDIO tla for Therme Group

Further plans call for 10 acres of new aquatic habitat, including six acres of constructed wetlands. The landscape is being developed in partnership with STUDIO tla and Trophic Design, with consultation from the Mississaugas of the Credit First Nation. Native plant species would be used throughout the site.

Updated Ontario Place master plan by Infrastructure Ontario

Construction is expected to begin in Spring 2026, pending ground thaw, with a targeted opening in 2029, aligning with previous timelines suggested by the Province. Therme projects 2.5 million annual visitors by the facility’s fifth year of operation.

UrbanToronto will continue to follow progress on this development, but in the meantime, you can learn more about it from our Database file, linked below. If you'd like, you can join in on the conversation in the associated Project Forum thread or leave a comment in the space provided on this page.

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Related Companies:  BDP Quadrangle, Crozier Consulting Engineers, Diamond Schmitt Architects, LEA Consulting, RWDI Climate and Performance Engineering, STUDIO tla, Urban Strategies Inc.