A good adventure books to read

I haven't read many adventure books but I do know of the Reckless series by C. Funke. It is about a boy/man finding a fantasy world behind a mirror where he becomes a treasure hunter. I have only read one book of the series, but I think it is worth a try.
Another book is by a Dutch author. The Dream Merchant by I. Hoving. It is not really about treasure hunting but more about an adventure through time and dreams. It was a bit complicated but I enjoyed it.
These two books are children/young adult books fyi
That's all I've got :(

the emerald atlas by john stephens