Which one is the correct verb form in the following sentence?
The craziest thing I've ever done is go / to go / going scuba diving in Belize
Some people say that both the to + verb and the ing forms are correct, because you need a noun there and the bare form is a verb; other people say only the to + verb is the correct one here, because the ing form only applies when you reverse the sentence (going scuba diving is yadda yadda) and not when you place the subject in the end.
I know many people would use the bare infinitive to be quicker while speaking, but that just sounds wrong to my ears as it's a verb!
Can you please tell me, once and for all, which is the correct verb form?