The White Knight Camp is located outside of the Grotworm Lair, between Rimmington and Port Sarim. Several unnamed White Knights can be found in the camp, led by Sir Rebrum.
There are very few Knights in the camp; the bodies of the rest can be found on the first level of the Grotworm Lair.
There is a small Summoning obelisk for recharging Summoning points located in the camp, directly by the entrance to the Lair.
You can teleport here once a day with Remora's necklace after the Song from the Depths quest.