An hour sounds like a long time to float.

As a first-time float tank user with a love of statistics, I was across all the major numbers before dipping a single toe in the water. I knew, for example, that my toe would go into a double bed-sized pool filled with 400kg of Epsom salts and 1,000 litres of water.

What I wasn’t prepared for was how hot it would be: both the room and the pool thrum at a steady 34.5C. Or that halfway through the session I had to sit up because I was feeling a bit claustrophobic from the humidity.

According to City Cave, a float therapy centre with about 30 locations in Australia, using a float tank “helps your body enter a deep state of relaxation, so your brain can enter a place of rest and repair”.

I’d gone from a 17C day in Sydney, to an air-conditioned room watching a video for first-timers (“There’s nothing like your first time”), to a small room with walls of cool black stone and the hot heavy air of a tropical island. The humidity hit the back of my throat like a warm punch, which surprised me, because the City Cave website had told me that 34.5C is also the same temperature as my skin. Who knew I was actually, always, this hot?

To address this, and for hygiene reasons, the first task is to put in earplugs (provided) and take a cold or lukewarm shower. Then, it’s time to get into the pool. I follow the instructions that Keira from the front desk gave me earlier: hold the handrail and step in, one foot at a time. Squat down and lower yourself into the pool, where you’ll find, once you sit down, that the water comes up to your waist. What does 34.5C water feel like on 34.5C skin? Kind of like being in a bath which is just right: there’s no need to lower yourself into the water gingerly, nor lament the tepid temperature and reach for the plug.

Once seated, it’s surprisingly easy to float. I just lean back, extend my legs, place my arms by my sides, and let the saltwater do the heavy lifting. (If you get any salt water in your eyes, don’t panic – there’s a spray bottle with fresh water nearby.)

What’s remarkable is how quickly I felt as if I weighed nothing. The only part of my body I was sure still existed was my head, and that was only because it was having these thoughts. The closest I’d ever felt to this sensation of lightness before was at the end of a yoga class, when you get to lie down in relief that your exertion is over.

But an hour is a long time to float in sensory deprivation. You can break it up by having music play in the first and last 10 minutes of the hour, and by turning the lights on and off. Or you might, like me, become curious about what it feels like to gently push yourself from one side of the pool to the other with your arms outstretched like a paper cut-out doll (very calming). You might also place your hands on your chest like you’ve seen otters do when they float, to see how it feels (like being a giant otter).

I never fell asleep but there were pockets of time where I was no longer focusing on my breathing, and my mind had gone wandering in a way that was without thoughts.

There was at least one long period of stillness. When I moved my arms again, there was resistance – the salt had had time to dry around my skin. By the time the music began to play in the last 10 minutes of the hour, I was so chill that I could feel the bass notes through my feet, which I didn’t notice at the start. And then a recorded voiceover played to let me know the hour was over. I couldn’t make out what was being said because of the earplugs.

But I knew it was time to go from brined skin and deep relaxation back to the world of weightedness once more, via a cold or lukewarm shower. In a world that’s mostly sink or swim, an hour of floating didn’t feel that long after all.