Wat Tum Chiang Dao Cave about 1 hour north of Chiang Mai.
Actually the fee is reasonable 40 baht for foreigners and 10 baht for Thai from my understanding. I say reasonable because it’s well worth the experience.
The cave is large with a couple of additional long unlit passageways which require a guide and lantern for an additional 200 baht, I believe this guide and lantern fee applies to everyone. The guides wait in the coolness at a junction not far into the cave for people wish to employ their services. There is a graphic outside the entrance where you pay outlining how all the portions of the total guide fee are distributed. Masks are for sale 10 baht, temperature checks and hand washing are all required or available.
The basic front/main portion of the cave is wide, open, tall, well lit, and easily walked, maybe 200 meters. The lighting is just right, not too bright and giving a sense of the caverns darkness and shadowy sculpturing of the natural formations of stalagmites and stalagtites. A few shrines inside where worshippers can pay respect. Just outside the main entrance steps is beautiful clear cool pool of water with large well fed fish gliding about.
The steps are not many to gain entry to the cave and I’d have to say anyone who is mobile, young or old, can accomplish the experience. I strongly suggest flat shoes as the pathway floor inside is mostly small undulating bumps.