Recently deleted photos

The recently delete photos in a library are just database entires in the library's database. The image gets removed from all albums and projects and views (with database entires modified) and is only in the Recently deleted view. The original file remains untouched until the deletion is finalized in 30 days or earlier by the user.

As STCav pointed out rummaging around in the library's package is not for the user and doing so can irreparably damage the library.

The 'Recently Deleted' album is available within Photos app. It's not a good idea to go poking around within the Photos Library using Finder, as it's easy to cause permanent damage to the library. Why do you think you need to?