You can use the 72m waterslide, they have a waterfall, a jacuzzi, a pool outside and a lot of more.
The price: 0€ for you. It's included in your accommodation expences!!
How to get there by bus from the youth hostel:
Bus stop: From "Gesundheitsamt" to "Hans-Böckler-Straße/ Bad1", 7 Stops
Bus no. : 502
Mo - Fr
9.00 - 21.00 Uhr