Caves that go straight down are typically called vertical caves, pit caves, or shaft caves. They can also be referred to as potholes, sinkholes, abysses, or caverns, depending on their specific characteristics and formation.

Here's a breakdown of these terms:

* Vertical cave: This is the most general term and simply describes a cave that descends vertically.

* Pit cave: Similar to vertical caves, these are often deeper and narrower, resembling a well or shaft.

* Shaft cave: This term is often used interchangeably with pit cave and emphasizes the vertical nature of the cave.

* Pothole: Usually refers to a smaller, naturally formed vertical shaft in a riverbed or other geological formation.

* Sinkhole: A depression in the ground formed when the surface collapses into an underground void, often associated with karst landscapes. While not always vertical, sinkholes can sometimes lead to vertical caves.

* Abyss: This term is used for extremely deep and often unexplored caves, often with a sense of danger and mystery.

* Cavern: A large, natural underground chamber, often with a variety of features like stalactites, stalagmites, and other formations. While caverns aren't always vertical, they can contain vertical sections.

Ultimately, the specific term used depends on the context and the individual characteristics of the cave.