Looking at the Garmin 550t (t standing for topographical maps), you would be forgiven for thinking someone had handed you the previous version. It's so alike, that at first we thought that Garmin had just sent us the wrong unit.

Why? Well...

So you fancy a spot of Geocaching, but at the same time don't want to actually do any real thinking about it? Garmin hopes it has just the answer with the Garmin Oregon 400t. But is this the must-have GPS for treks? We head out and about to find out....