Where: Sati-Floatation, 40 Peel Street (off Hollywood Road), Central (tel: 2854-0877). A small, ground-floor shop has been converted into a pleasant space with two rooms containing flotation tanks and showers. Why: Floating is a unique, intense form of relaxation, and research suggests its benefits can last longer than the initial endorphin rush. Heart-rate and blood pressure drop immediately, and permanently lower levels can apparently be maintained by floating regularly. It's also thought the flood of endorphins can help alleviate long-term depression, arthritis, asthma and weight problems, and even help floaters give up smoking. Carl Lewis used a tank regularly before winning his two gold medals at the 1988 Seoul Olympics; the Australian Institute of Sport uses tanks when training its Olympic squads. The water in a tank is 25 per cent saturated with Epsom salts, which means it is five times more buoyant than normal sea water. A filtration system cleans the water when the tank is not being used. Who: Ho Sai-yiu is a businessman involved in property and construction; this is his only health-related concern. He first tried flotation on a recent trip to London, and on returning to Hong Kong and being unable to find anywhere to float he set up Sati-Floatation. He uses his own tank once a week. What: Each of the two private rooms has a shower and a futuristic-looking tank. You shower and insert earplugs before stepping into the tank and sliding the lid shut. The water is body temperature - 34.6 degrees Celsius - and its high saline content makes it feel luxuriously silky. On the inside of the tank are push-button controls for the interior light, hi-fi and video screen (athletes use it to watch repeats of perfectly executed sports moves, but Sati-Floatation staff encourage clients to experience flotation without TV when they first visit). There's an emergency call button in the unlikely event of your panicking. The water is only 30cm deep, but floating is effortless. I had expected to feel claustrophobic, but the high ceiling of the tank made it seem spacious and comfortable. The result: The neck and back tension I was experiencing before my float had melted away by the time I emerged. Afterwards I felt mentally alert and easily completed the work I'd set myself that evening. The 'zero-gravity' sensation and subsequent feeling of relaxation also meant I slept well that night. The bottom line: One hour-long float costs $399; packages of three and six are $1,080 and $1,980 respectively. The verdict: Floating is fantastic. The only thing to avoid is getting the stinging salt water in your eyes.