Ilighôn was one of two islands, along with Wavecrest, that made up the Eyes of Silvanus in the Sea of Fallen Stars. It was situated close to the mouth of the Vilhon Reach and benefited from the protection of reefs as well as the magic of the Emerald Enclave. 
The island was accessible via a gap in the reef, known as the farshore straits. This passageway was guarded by the Seven Sentinels of Silvanus, a group of water and air elementals who acted upon the direction of the enclave.
A unique property of the island was that it naturally negated all arcane magic. If a wizard were to cast any magic on the island it would immediately fizzle into nothingness; this included spells that may have been cast prior to arrival such as stoneskin or contingency. Any scrolls, rods, staves or other items with magical charges would cease to function and their use would ultimately be a waste of magical energy.
Divine magic was unaffected in this way, rather the island possessed a faith-magic zone, which improved the effects of certain magic of the gods. Although the nature of this boon wasn't fully known to the mortals of Toril, it was believed to have been a gift from the goddess Mystra to Silvanus.
- Calling, Elder and Springbrook Rivers
- These three rivers were formed from the pools of water surrounding the House of Silvanus. They roared down the Elder Spires, forming magnificent waterfalls.
- Eldath's Ring
- Grandlore Forest
- Covering over half its land, the Grandlore was easily the largest forest on Ilighôn.
- Great Forest
- The smallest forest on the island, located on its southern reaches.
- Lake Bluesprings
- This getaway for the island's residents was surrounded by otherwise wild and overgrown lands.
- A settlement of sorts that served as a gathering place for treants, some of whom were extremely old.
- While it wasn't a settlement so much as a collection of small groves, Druidhome served as a haven for elder rangers, priests and druids who wished to live their last years in service to the nature deities.
- House of Silvanus
- A holy site for the worshipers of the Forest Father located in the heart of the island of Ilighôn. It could be reached by the Hierophant trail, a walkway that led to the temple from the city of Sapra.
- This enclave city was a haven to those across Faerûn who sought to live away from what saw as the tremendous negative effects of wizards and their brand of magic.
- Jim Butler (1996). The Vilhon Reach (Dungeon Master's Guide). (TSR, Inc), p. 22. ISBN 0-7869-0400-3.
- Steven E. Schend (1999). Sea of Fallen Stars. (TSR, Inc), p. 13. ISBN 0-7869-1393-2.
- Jim Butler (1996). The Vilhon Reach (Dungeon Master's Guide). (TSR, Inc), p. 23. ISBN 0-7869-0400-3.
- Jim Butler (1996). The Vilhon Reach (Dungeon Master's Guide). (TSR, Inc), p. 24. ISBN 0-7869-0400-3.
- Bruce R. Cordell, Ed Greenwood, Chris Sims (August 2008). Forgotten Realms Campaign Guide. Edited by Jennifer Clarke Wilkes, et al. (Wizards of the Coast), p. 185. ISBN 978-0-7869-4924-3.