The Intel Map displays portals in the Ingress game. Are there undiscovered portals that do not appear in this map?
I know that new portals are added from time to time. What I want to know is if there are existing portals that I can find by exploring with the game running.
Edit 2013-01-15: I am aware that it is necessary to zoom way in on the Intel map to see low-level and unclaimed portals. I am specifically wondering if there are portals that do not appear on the map at any zoom level because they have never been visited/discovered.
I ask because the portals on the Intel Map have notes like, "Discovery: Khayman 01/14/2013". Are these the names of players who have discovered previously hidden portals - or are these the players who submitted geotagged pictures to get portals added? I am skeptical of the latter possibility because some of the portals in questions are post offices and libraries and do not have pictures.