A few minutes of searching should get you the correct coordinates, but extracting the cache from the underworld may be a bit more difficult. You will need a special TOTT (see gallery)
N ab cd.efg W hij kl.mno
a. Harpagophytum
b. Charlie Daniels song
c. 1953 3D western
d. Jane Yolen 1988
e. 1907 Chestnut St. Philadelphia, PA
f. seaweed
g. French penal colony
h. Datura Podophyllum
i. 1711 Lawson Road Mesquite, Texas
j. Andrew Neiderman
k. 6664 grams found Friday the 13th, 2014 on a night with a full moon
l. Sweetwater River Wyoming
m. Stillwater Reservoir East Fork Trail #1119
n. California coast near Point Arguello
o. Rock Bridge Memorial State Park
You can validate your puzzle solution with certitude.