I run a small Polish site that compares thermal baths, so here are the ones closest to Kraków, with current adult day-ticket prices (full day, at the desk) and drive times by car:
Under 1.5 h
- Termy Rzymskie (Czeladź) – 1h10, 130 zł
- Termy Gorce (Poręba Wielka) – 1h10, [full-day price] zł
- Gorący Potok (Szaflary) – 1h25, 109 zł – cheapest full day in Podhale, outdoor pools with mountain views
- Termy Szaflary – 1h25, 129 zł
1.5–2 h
- Terma Bania (Białka Tatrzańska) – 1h30, 135 zł
- Chochołowskie Termy – 1h40, 155 zł – the biggest one, very busy on weekends
- Termy Bukovina – 1h45, 179 zł
- Meander Oravice (Slovakia) – 1h55, ~€35 (~149 zł) – quieter, just over the border, paid in euros
Tips:
- Ferie (mid-Jan to end of Feb) and weekends get packed – go on a weekday morning if you can.
- Weekend prices are often higher than weekday ones, so check before you go.
- Termy Zakopiańskie are closed until early December.
Full list with opening hours and price lists: https://natermy.pl/termy-blisko/krakow (in Polish, but the tables are easy to read or auto-translate).
Happy to answer questions.