There is a rumour that Delaware is the only State without even a single cave in the USA. This is not true: Delaware has exactly one cave. However, it is a wild cave and in order to protect it, we will not publish anything about it.

Delaware is the second-smallest state in the United States, located on a peninsula which heads down south, along the Mid-Atlantic Coast. It is bordered to the east by the huge estuary of the Delaware river. The whole country is flat, low (less than 137 m asl), part of the Atlantic Coastal Plain with flat, sandy, and, in some parts, swampy ground. Only along the northern border has some hill country.

The main underground thing about Delaware is the Underground Railroad. For non-American visitors: this was an underground organization which helped slaves before the Civil War to escape to the northern states. There is not much underground about this railroad, and definitely there is no railroad. It is a metaphor for clandestine routes and safe houses.

Actually Mississippi and Delaware are the only states in the U.S.A., where we have not listed a single site.