* High tree density: There are many trees packed close together, with little space between them. This creates a thick canopy overhead.

* Limited undergrowth: Due to the dense canopy, very little sunlight reaches the forest floor, which limits the growth of shrubs and other vegetation.

* Limited visibility: The dense foliage makes it difficult to see through the forest.

* High biodiversity: Dense forests often support a wide variety of plant and animal life, due to the abundance of resources and shelter they provide.

* Important ecological roles: Dense forests play a crucial role in regulating climate, protecting watersheds, and providing habitat for many species.

Here are some examples of dense forests:

* Tropical rainforests: Known for their incredibly high biodiversity and dense canopies.

* Temperate rainforests: Found in coastal regions, they have tall trees and a thick understory of ferns and mosses.

* Old-growth forests: These are forests that have been undisturbed for a long time, allowing them to develop a dense canopy and complex structure.

It's important to note that "dense" is a relative term. What constitutes a dense forest can vary depending on the specific location and type of forest.