Have you ever looked at a mound of brown-green, slimy seaweed and thought, gee – I wonder what it’s like to sit in a tub filled with that stuff?

Probably not. Few people do.

The Irish, however, have been making the most of seaweed since the 12th Century, when monks would harvest a type of seaweed known as dillisk from the rocky coastline and distribute it among the poor for nourishment. Later, it was used to replace chewing tobacco, to eliminate parasitic worms and – apparently – quell “women’s longing”. I could understand that: the stench of fresh seaweed washed ashore is enough to quash any desires I have too.

Nowadays, we know that seaweed is rich in vitamins, so it’s used in beauty products such as bubble baths, shampoos, shower gel, facemasks and scrubbers. Thalassotherapy, a treatment whereby seaweed is added to bathwater, is a European method known for softening skin, improving circulation and draining the lymphatic system. Seaweed is also used for curing liver problems, cellulite, obesity and depression. I have none of those things (we won’t talk about the cellulite), but I do like baths. And that’s how I ended up at Kilcullen’s Seaweed Baths in County Sligo.

Bathhouses came to the Emerald Isle during the Edwardian era, with about 300 seaweed-specific spots scattered around the country at the start of the 20th Century. Nine of those were in County Sligo. Today, thanks to the introduction of modern spa treatments favouring sweet-smelling chemicals, only two remain, Kilcullen’s included.

Edward and Christine Kilcullen are the fifth generation to own the bathhouse, an Edwardian black-and-white building that became famous for its modern appearance when it opened in 1912. Christine greeted my friend Scott Sporleder and me when we arrived, the entire spa smelling of fresh of seaweed and brine mingled with an earthy beach scent. Assuming Sporleder and I were a couple (we weren’t), the baths were filled and prepared for us in the same room.

“Well, maybe you’ll see something you’ve never seen before,” she said when we corrected her. Considering I had never even heard of seaweed baths until the day before, I was sure I would.

Happy to prolong an awkward experience, Sporleder and I watched the seaweed steaming process before dipping into our baths. First, a pipe emitting scorching vapour softened and purified the vegetation; then the seaweed was piled like…well, seaweed, in our very own porcelain basins of pleasure, quickly turning the water a murky amber colour. Sporleder averted his attention to photographing the experience while I changed into a bathing suit. Climbing into the tub, I slid my body underneath the tangled seaweed and reclined. I pulled the oily strands between my fingers, added some hot water to the tub, and rubbed the flora into my skin.

Once Sporleder was finished photographing, we alternated between the cedar wood sauna – a box that left only my head exposed – and the old-fashioned, brass-tapped tubs. The steam inside the box opened our pores to the biting Irish air, and the bath infused the seaweed oils right into our skin. The treatment is supposed to be followed by a cold shower – but I’m a Canadian who’s against being chilly.

When I emerged an hour later, I felt as if salt was encrusted in my skin. Delightfully, I was tingling from head to toe, my skin feeling as though it had been purged of its toxins. But I was also sure I smelled of seagulls and sea urchins and pungent seaweed. Essentially, I felt like I imagine a mermaid would.  

Two weeks later, I found myself at County Sligo’s only other remaining seaweed bathhouse, Voya Seaweed Baths. While Kilcullen’s is an old-fashioned bath house once considered modern, Voya offers the modern experience that travellers a hundred years from now will see as old-fashioned. Rather than smelling like ocean brine, Voya smelt of spa oils and luxury beauty products.

Filled with seawater pumped straight from the Atlantic, just outside the front door, the baths at Voya use seaweed that is hand-harvested under a special license in unpolluted conservation areas where the vegetation can be assured of its purity. It’s all certified organic.

But unlike Kilcullen’s, where the seaweed prep is on display, at Voya the focus is on tranquillity. Soft classical music drifted through the ceiling’s speakers. A candle burned on the sill. I sat in the steam room and nearly suffocated myself before submerging into the silky, seaweed-infused water. I put away my camera. I relaxed.

Rubbing the seaweed between my fingers, I was left with thick globs of oil on my hands. I massaged the oil through my hair and let it sit there for a few minutes before rinsing in the tub. The oil kept my hair shiny and smooth for days.

Later, I met my friend Julia Smith Porter in the change room and asked her how she felt.

“Amazing!” she said. “Except you would have hated my tub. I found a giant dead spider.”

Maybe I’ve had my fill of the seaweed baths for now.