A vertical watercraft has lately become a fixture of Seattle’s weekend waterfront. Part ship, part sweat lodge, the registered, fully motorized vessel is a floating sauna, offering passengers a unique chance to take a 200-degree shvitz or an invigorating cold plunge right in the shadow of the city skyline.

Multidisciplinary firm goCstudio conceived the aquatic riff on Finnish sauna culture as a side project one winter and solicted help from peers to make it happen. “We wanted to figure out how to engage the water surrounding the city year-round,” explains principal Jon Gentry.

Crowdfunded on Kickstarter and built using warehouse space lent from a local brewery, with support from students and volunteers, the project was a 19-month collaboration—one that continues to bring the design community together.

Following the sauna’s maiden voyage last fall, goCstudio began inviting backers aboard, six at a time, for cruises on Lakes Union and Washington. This year, says Gentry, they hope to get even more people involved: “We’re going to program events that pull in the community that funded this, so everyone who wants to gets a chance to experience it.”