I often get asked whether there are guides or tour companies offering proper, non-tourist caving trips in Thailand. There are very few specialist cave guides or companies running 'proper' caving trips.
Listed below are the companies that I know about. I would be very interested to hear from any other guides or tour companies and I will happily add your details to the the list.
NOTE: these tour companies have not been vetted, checked or endorsed. I can not guarantee the quality of the tour or the safety standards of the operators. Caveat emptor.
In the north of Thailand the best bet for advice on caving is probably Cave Lodge in Mae Hong Son. This is run by a very experinced Aussie caver who can rent you equipment, advise on the caves to visit and arrange guides if required.
At Tham Mae Lana in Mae Hong Son the local villagers run a guiding service into the upstream entrance of Tham Mae Lana and other nearby caves such as Tham Pakarang.
In Chiang Mai there is Chiang Mai Rock Climbing Adventures. Their website only mentions caving courses, not guided trips, which are held at Crazy Horse Buttress a few kilometres to the south-east of Chiang Mai.
Near Chiang Dao Cave in Chiang Mai the Chiang Dao Nature Resort can organise guides and transport to nearby caves such as the 2 km long Tham Ki Mi.
Although the tourist brochures found in Chiang Mai for The Peak Adventure lists a three day trip to the 100m deep Spirit Well (Bor Nam Phi) in Mae Hong Son this trip is not mentioned on their website (NB: this website is also flagged as a threat by AVG).
Nearer to Bangkok is Saraburi Adventure. This company is Thai run, but the director speaks good English. The website only mentions trips to a single long stream cave in Saraburi.
Hyperventure, another Thai run company, advertise tours to Tham Nam Lot Ti Pu Che in Kanchanaburi and Spirit Well (Bor Nam Phi) in Mae Hong Son.
In the south of Thailand the options are a lot more limited and I don't know of any companies running caving trips. More adventureous trips beyond the normal show cave tour can be arranged with the guides at Tham Khlang near Krabi. On Ko Lanta Mr Lek, the original guide at Tham Mai Kaeo, will still lead parties to wild caves nearby. He can be contacted on 0870 506086.