Here is the gadget's readout.
The stats: 9.5km (I reckon deduct 1.5km from that), 1 hour and 1 minute (for me). I topped out at 25.5 km/hr when I slipped down the bank with Thrust and FogHorn on the way home. We burned 684 kilo Calories!
I reckon the gadget had not obtained a position when I told it to start tracking us, which may have resulted in an extra 1 - 1.5km. Who knows. It also reckons we started at an altitude of 377 meters, and the picnic area was at 93m. Next time remind me to turn this thing on before the start! This technology always baffles me.