Guest Passes let you share your photos that aren't public.
Anyone can see your public photos anytime, whether they're a Flickr member or not. But! If you want to share photos marked as friends, family or private, use a Guest Pass.
If you're sharing photos from a set, you can create a Guest Pass that includes any of your photos marked as friends, family, or private. If you're sharing your entire photostream, you can create a Guest Pass that includes photos marked as friends or family (but not your private photos).
Anyone can see this photo 
Saved!
Anyone will be able to see this on the map