The coordinates are just a general area for this cache. Either side of the road will work fine.
The Big Island is unique in many ways, one is the form of grafiti found here, that is not found on any of the other islands (at least not yet). As you drive along the highway you notice names, phrases, and pictures, formed from alighing the white coral rocks on the black lava fields. A interesting and eye-catching creation can be found along the roads, that in no way is bad for the environment.
What is involved for this cache, is to either find coral rock along the ocean and carry to this cache, or to find old grafiti that is incomplete and salvage rocks from there. Be create and design something on the lava and then take pictures and upload them to this site to verify your find. Have fun and good luck - Aloha