The cache is not at the posted coordinates.
Only I know the key to solving this puzzle;
and naturally those who understand this.
3 T N 4 F I V E T N N Y 2 B G
8 E S I R E D I H I E T 8 L R
S A I B N 4 0 G I N E E N A E
I L X L P E 0 H R E T N E C Y
X Y T A U R N T T T F I E K E
D T E C R B I E Y E I N T E I
E X E K P L N E 7 E F B R I G
R I N 1 L U E N 0 N 5 L I G H
E S G R E E N G R A Y U H H T
D E R F I F T Y B L U E T T Y
Congratulations to first solver LydiaSimmons and first finder JuniorWences.