The Spirit Temple is the last temple in The Legend of Zelda: Ocarina Of Time, and is the most hazardous temple as well. It holds the boss Twinrova (Koume and Kotake). This temple requires one to have the power of the silver gauntlet and the youth of a child (Young Link and Silver Gauntlets).
The Spirit Temple, being the last temple, is mostly a pyramid-like temple that has quite a few puzzles. You meet with Nabooru, the Spirit Sage. Nabooru plans on thwarting against Ganondorf, leader of the Gerudos. Link offers to help Nabooru by retreiving the Silver Gauntlets, gauntlets that can hold 2 times the weight of a large rock (apparently, it doesn't work for the Biggoron Sword). After Link defeats the Iron Knuckle mini-boss, and gets the Silver Gauntlets, he sees Nabooru get sucked into a hole of darkness. After Link re-arrives as an adult he faces two more Iron Knuckles, one being Nabooru. Twinrova will emerge after defeating Koume and Kotake.