A forest is an ecosystem where trees are the predominant lifeforms of the area. Smaller tree-covered areas were known as woodland or woods. A rainforest was a type of forest characterized by the abundant amount of rainfall it received. Earth's oceans also featured kelp forests.
The colony on Terra Nova was surrounded by several forests. In 2151, Lieutenant Malcolm Reed of Enterprise NX-01, saw a person in the forest and followed him until he arrived at a cave entrance. He informed Captain Jonathan Archer over com about his sighting. (ENT: "Terra Nova")
Seed pods that had been constructed and sent into space by scientists during World War III survived the annihilation on Earth in an artificial biosphere and after century had grown to forests too large to return...Hence Starfleet built its first Starbase with the domes as accoutrements to the station.
On Rinax, there was a large forest behind Neelix's childhood home. He would explore the forest every day with Alixia and his other sisters. In the forest, they would make up stories. (VOY: "Once Upon a Time")
Next to the settlement on Meridian was a forest and behind it a garden with a pond. Deral suggested to walk to the place with Jadzia Dax in 2371. (DS9: "Meridian")
The planet Nepenthe seemed to possess several forested regions on its surface, one of which contained the home of Will Riker and Deanna Troi. (PIC: "Nepenthe")
Some known forests included:
- The Great Forest, part of the Talaxian afterlife
- Sherwood Forest, the home of Robin Hood and his outlaws
- The Forest of Forever, a setting in The Adventures of Flotter series of holoprograms
- The Bestri Woods on Bajor