A "Delver" is a subdivision of "Psychonaut" that tend to take deliriant class substance's such as Diphenhydramine, Datura, Dimenhydranate etc.
Joey "Yo are you ready for our next acid trip this weekend."
Chris "Nah man, I was looking forward to do Datura again."
Joey "Oh are you a Delver or something?"
A Delver is a person who prefers to take deliriant class psychedelic substances over the other options. Substances such as DPH, Scopolomine,Datura, etc.
Tim "I'm a Psychonaut but I like Deliriants"
John "Ohhh, so you're a Delver?"
Tim "Umm, yeah I guess I am"