As the banner says, if you qualify, you can log it. All OCNA Challenge caches are locationless type, arranged as Geo-Art in The Gulf of Mexico.They are all "unknown" (?) caches, owned by a special Admin account, OCNAChallenges. Do you have an idea for one? Feel free to contact us.
They Found it! level 2: Very simple. Receive at least 50 found it logs on your owned caches on the OpenCaching North America website!
Verification: For the They Found it! challenges, you need do nothing really, except qualify, as the number of found it logs on your owned caches is displayed on one of our site statistics pages: Here. Keep in mind that for many other of our challenge caches, we do have the equivalent of a Groundspeak "my finds pocket query", and that .gpx file is easily imported into GSAK, or any similar stats program.