Building off this previous post, today I learned a new command in Netrw: the 'special command'.
When navigating, enter
x over any file, and your operating system will open it with its tool of choice (Preview for images and Finder for directories on a Mac, etc.). This is great for exploring a directory.
From the Netrw help:
Certain files, such as html, gif, jpeg, (word/office) doc, etc, files, are best seen with a special handler (ie. a tool provided with your computer's operating system). Netrw allows one to invoke such special handlers by: * when Exploring, hit the "x" key * when editing, hit gx with the cursor atop the special filename (latter not available if the g:netrw_nogx variable exists)