Recursive unrar of several folders
find Photos/ -name '*.rar' -execdir unrar e {} \;
unrar has built-in recursion using the -r Recurse subdirectories switch.
unrar x -r <parent directory>
Extracts contents of all subdirectories under <parent directory> into each subdirectory, keeping any directory structure that exists in the .rar files. Use e instead of x if directory structure is unwanted.