This is one of Mercury's favorite spots to hang out. We run on his island on most weekends, and he loves to watch the helicopters come and go from our apartment. You can take the bus to get here, just stop at Nodeul station. The bus routes that run to Mercury's Island are 150, 151, 152, 500, 501, 750B, 751, 752, N15, and 6211.
To get the final coordinates, first go to ground zero. Then go to this website on your smartphone: https://geotrailsw.com/mob
Input the mob number 3867. Once five devices are within the radius of the cache, the final coordinates will appear. Make sure the website works on your phone before coming out!