Dagobah, a swamp planet, clouded with the 'living Force' but also has a 'darkside' nexus which occured when Yoda beat a dark Bpfasshi Jedi (the Force passing into a tree) clouding all those from a Force presence on Dagobah.
Here was the hiding place of Jedi Master Yoda during the wrath of the Empire.
Though the planet is a large swamp with trees and little light, the notable feature of the planet is that it has so much Force activity that it hides Force signatures, making it a perfect place of exile as a person cannot be tracked.
It was also here that Academy founder, Luke Skywalker established himself as a Jedi Knight and discovered that he had a twin - a sister - Princess Leia Organa (Solo would be later added to the name).