Plenty of differently themed saunas, steam baths, hot tubs and cold tubs, reclining chairs indoors…read moreand out and a pool in which you can swim from indoors to outdoors. And there's an hourly saunaaufguss in two of the saunas
Restaurant is so-so - okay if you find that you need a snack but not good enough that I'd plan ahead of arrival to eat there.
Staff generally doesn't speak English and all signs etc. are in German, so as a service to those who don't understand German language and/or German sauna/spa culture here's a quick intro to avoid getting you into awkward situations with staff and other guests.
The biggest shock to people from some other cultures will be that saunas are mixed gender and swimwear is not allowed inside them, meaning that people are in the nude. You can cover up in your towel if you're shy, and outside the saunas and in the big pool bathing suits are allowed, but nowhere are they required. In addition there's a section for women only (with a couple of saunas and hot and cold tubs I believe, but naturally I haven't been there). This mixed gender nudity is completely normal in saunas in Germany (and several other civilized countries) and it is not connected to anything sexual. I'll assume you're smart enough to figure out that it's not cool to ogle nude people so I don't have to tell you.
In the sauna you're supposed to sit on your towel, and to not place your feet directly on the bench below. A large towel makes this easier. Also, a short physics lesson for first timers: You might think that it's warmest close to the sauna oven, which means on the lowest shelf. But hot air tends to rise, so actually the higher you sit the hotter it gets. If you've never been in a sauna before I recommend starting low.
Stay quiet in the saunas, and don't be loud anywhere on the premises. People are here to relax, and loud talk is frowned upon. Also, mobile phones are not allowed so leave them in the locker. I assume the same goes for laptops, cameras and other gadgets and I can't recall ever having seen a piece of electronics in here.
Do not go directly from the sauna to the cold tub or pools. Rinse off in the shower first. Yes, it's soo nice to run out of the sauna and jump directly in the cold water, but hundreds of people go in the same water and none of us want to swim around in the others sweat so basic hygiene is to be observed.
There a "saunaaufguss" in two of the saunas once per hour. In practical terms this means that a member of the staff will come to the sauna, throw some scented water (which quickly evaporates) on the stones of the sauna oven and swing a towel around to mix up the air. The effect of all this is that you get a whiff of whatever the water is scented with and, most importantly, the higher humidity makes the air feel a lot hotter. The time and scent of the next aufguss is announced on a sign next to the sauna, and it's advisable to be there a few minutes early as it tends to get crowded. Again, if you're new to saunas I highly recommend starting out on the lowest bench. Also, opening the door during the aufguss is frowned upon as it lets hot air out and cold air in so don't leave prematurely unless absolutely necessary.
Do not reserve reclining chairs by leaving your towel on them when you're not using them. Or at least that's what the signs say, in actual practice you often see 90% of the chairs empty, yet still with towels and other crap marking them as reserved, which can make it difficult to find a seat, especially if you're two or more people who would like to sit together.
It's highly advisable to wear slippers as the floor is slippery in many places. Also, your towel is not unlikely to get drenched so bring an extra and leave it in your locker so you can dry off properly once you're done. Bring a bottle of water as sweating in the sauna can make you thirsty, and bring soap and shampoo as well.
