Can I apply for a DTV visa in Thailand for diving training?

Diving is not recognized.

There was a man who had applied DTV with diving and already rejected

That’s why means that diving can’t

What might be an issue with the diver training route, the individual courses are I believe max of two weeks. Now if your not already a qualified diver and enrol for all the courses you can, then that might be an acceptable requirement. If you just applied for the first module, which is probably only five days, but don't know for sure, the Embassies might not accept it, plus if you did apply after booking the initial diving module only and they didn't accept it, then you lose whatever visa fee you've paid. Whichever Embassy or consulate you intend applying to, best to call or email and ask them first.Keep us posted please.

Not sure at all