Temple Island is one of the five islands that make up the 5th Age (or the age of Riven), Temple Island is made up of two smaller isles. The arrival point of Riven is on the first of these two isles and it is in the small domed ‘arrival’ chamber that Gehn installed a cage in an attempt to recover any Linking Book that a traveller linking in may have had. The larger Golden Dome houses the mechanism that directs energy to Gehn's Linking Book (Fire Marble) Domes, the Star Fissure Telescope, and the rotating Gateroom.
The Star Fissure Telescope is the departure point in the game.
On the second isle is the Temple itself which is reached by crossing a short footbridge that links the two isles. It is in the Temple where offerings to the Wahrk were left and where Gehn had a large imager installed.
As you cross the footbridge and enter the cavern pathway you first reach a room where the imaging device and chair are situated, Gehn would sit in this chair and project his image onto the imager in the Temple, this was his way of controlling the Rivenese that were granted access to the temple.
Outside of the Temple is a Maglev (Magcar) station where a Maglev would take you to Jungle Island.