The above coordinates are for the trailhead that will take you to the Knight Who Says Ni! It is not the location of the cache. To get the coordinates to the actual cache location and open the Holy Cache you will need to bring the Knight a sacrifice. Let him speak for himself: The Knight Speaks! A transcript can be found here.
Within the Houston area there is a Shrubbery that should appease the Knight. Attached to the shrub is a metal tag with the coordinates of the cache as well as a key that will allow you entrance to the Cache itself. The coordinates alone will not be enough - you need the key! The Shrubbery should be presented to the Knight (with appropriate words of praise and general exaltation - he likes that.) Once the sacrifice is made and you have found the Holy Cache please return the Shrubbery to any Houston area cache you desire within 36 hours please so other pilgrims have a chance. The Shrub is weather proof so you can place it outside of the cache and please post a note on this page stating where you leave it.
This is a physically demanding cache that requires the crossing of two gullies that will be wet after rains. The cache is over .4 miles as the raven flies but will be longer if you manage to "follow" the trails. Trails can be difficult to find especially as you go deeper into the forest so make sure you mark your starting point - few brave souls venture this deep and live to tell the tale. Then there are the beasts - I have never encountered as many vile, palm-sized spiders as I have along this path. I don't know my serpents very well but I have seen black venomous creatures in the water and on logs, so beware. I won't mention the Poisonous Ivy because I did not look for it but no doubt it's there. Finally, the ever-present mosquito alone will at some point make this a miserable crusade.
One final thought. As you curse Sir Wyz along your journey - and you will - remember this: You must only do it once. He had to pass this way thrice and, well, you'll see. God Speed and may the Knight Who Says Ni! look on you favorably and allow you to pass this Dark Wood safe and unharmed.