Perth's largest magnesium pool is the headline here, and it earns it. Merse took over a stretch of Scarborough Beach Road in Osborne Park and filled it with warm mineral water, cold plunge pools and two kinds of sauna. The hot-rock room for the purists. The infrared for everyone easing in. Between rounds there are monsoon showers and a steam room, then the Rejuvenate Lounge, which is where the technology lives. Compression boots. LED in four colours. Massage guns and sound healing on a loop. It is a lot of recovery under one roof. You will leave loose. Come early. It fills.