This is a bonus cache for the Adventure Lab cache "Standish's Lost Heritage". It can only be found by gathering information revealed as you do the Adventure Lab. The final screen of each stage of the AL will reveal to you the digits to substitute in the following coordinates to find this bonus cache.
N 53° 34.ABC W 002° 40.DEF
Va n ynetr gerr orgjrra gur sbbgcngu naq gur srapr nobhg fubhyqre urvtug. Fvapr jr cynprq guvf pnpur rkgen oneorq jver unf orra nqqrq gb gur srapr ****CYRNFR OR PNERSHY****