How can I batch rename subdirectories and files in order to replace whitespaces with underscores?

Question

I am using Ubuntu and Arch-based OSs and I have tons of files that I have to rename. I have used this so far.

    allfiles=$(find ./ -type f -name "*:*")

echo $allfiles

find ./ -depth -name "* *" -execdir rename 's/ /_/g' "{}" \

It has renamed the main folders, but not the subdirectories.