Here is a list of some of the hardest caches known to humanity.
- No Further South From Here
- A virtual cache at the south pole.
- A physical cache in Antarctica.
- Shelter II
- A micro cache hidden somewhere on a rest stop shelter of an interstate in Indiana. Teams of people sometimes numbering as many as 15-20 scoured the shelter for two weeks before someone came up with the find.
- You've Got To Be Kidding Me...
- A difficult micro that warns you may get angry searching for it.
- The Journal
- A puzzler rated 5/5 in Illinois
- Tube Torcher
- A great multi in NC. The original was archived, but a sequel has been published.
Too Insane For Categories
- International Space Station
- A cache located on the International Space Station. Only 1 person has logged it so far.