Interesting plot twist. I signed up at the geocache website after finding a couple dozen within my natural drift of daily activity.

I pulled out my Garmin, an older model eTrex Vista and started plugging in lat/long. I picked one that based on the description I could drive to with a couple hundred feet based on my knowledge of the area. The GPS said I was 20 miles away. Not right. I had my smartphone with me and went online, double checked the coordinates. Plugged em' back in, nothing.

I read another cache that I knew was at a fast food joint based on the description, so I drove there. Fired up the GPS, fired up the website and the coordinates don't match between the two. Still off by about 20 miles.

Frustrated I went home and long story short, my setting for reading lat/long were different in my GPS than what the website gives. I recall letting some friends play with my GPS last summer on a cabin trip and they must have jiggered a setting.

I restored the defaults on the GPS unit, located another geocache within a mile of house based on the description and sure enough it matched right up.

ITS NEVER THE WRONG TIME TO CHECK YOUR GEAR. NEVER ASSUME ITS WORKING PROPERLY.

Lat Longs are the most universal of the coordinate systems. However, you still need to be aware of your Datums. Always double check your settings and the coordinates you are using. I will always use a map to triple check, by plotting to see any errors.

For UK sites they also give OS grid references, and provide a link to convert to other systems.