Actually you need nothing special to have a sauna. The most important equipments are flip-flops, bathrobe and a sauna towel. But not every towel fulfills the needs of a good sauna towel.
The German magazine "Ökotest" has tested different sauna towels. Look here for the most important results.
To begin: regularly sauna visits restore the immune system and the defensive forces. You are better protected against colds and you do something for your psychical balance, too. And furthermore positive is, that you don't need much for having a sauna. But much important is high quality material in your sauna towels.
Sauna towels are made by cotton. Cotton is very absorbent and allows also hot temperatures while laundering. Averagely a sauna towel is 70x200 or 70x180 cm sized and therefore smaller than normal bath robes. The magazine "Ökotest" has tested 14 different sauna towels.
Three of them get the grade "very good", seven "good" and four "satisfactory". But the magazine noticed that nearly every sauna towel shrinks at laundering and some of them curl up strongly. Four of them are equipped with tenderizers which are moisture repellent. But such tenderizers have nothing to do in sauna towels: they have to absorb moisture!
So: When you want to buy a sauna towel pay attention that it is made by absorbing material as cotton, renounce tenderizers and choose the bigger size, because the towels tend to shrink.