In the days of iOS 8, we had arrows leading from photos to album view. While the navigation arrow is still there, now, there’s an easier way. If you’re viewing a single photo, with one swipe of the finger you can return to viewing the album.
To try the Photo shortcut, open Photos, select an album, and tap a picture.
From the opened photo, swipe down with one finger. You're back to viewing the album.
Top Image Credit: Lisa A / Shutterstock.com