Well this would be concerning

Not quite as damp as the GPS would suggest

 

During Desert Storm, & the "sorties in the thousands", my GPS was often off by hundreds of yards, or more. During the solar flares a few weeks ago, I got a single reading that was off by about 14 miles.

GPS is far more reliable & stable than it's predecessor Loran was. But on occasion, selective availability, spoofers, and natural anomalies can throw it off a bit. Aircraft that rely on GPS for navigation have redundant systems.

 

stay where you are and when the tide comes IN, your GPS will be right !
On a more serious note, I use Garmin and often check it's accuracy when crossing a railway line as the road and the railway are well established intersecting points. I have found mine to extremely accurate

 

With a reading like that, you would be in Death Valley, CA. I think not, since Death Valley isn't oceanfront property. Yes, GPS lies!