First stop was the 4.8 mile round trip to the Lone Star geyser. We hadn't checked the expected time of eruption, but went anyway, managing to arrive by bicycle 10 minutes before the 3 hourly eruption was due. Beautiful elk and red squirrels bounded across our path on the way. Just 6 of us watched the magnificent 45 foot high eruption.

We followed up with the Fairy Falls trail in rain and thunder. Caroline was barely visible under a full set of waterproofs with hood over a sun hat. Relaxing part walk, part bike ride clocking up another 5.2 miles.

Our third adventure of the day was 2.4 miles of boardwalk at Norris, yet more geothermal delight.

Finally we planned to do the Elephant Back Mountain trail. However, several bison traffic jams held us up, this particular fellow brought us to a complete standstill.

We gave up and joined in the bison watching once the bison were a safe distance away. Incredibly small children were just 6-8 feet away from a large bison – we have seen the photos of bison chasing and goring people. A number of people have died from animal attacks here. Yellowstone is all about getting up close to the wildlife for many.

It's hard to take seriously the signs saying 'Danger, thermal area, thin crust' with 1,000lbs of bison walking on it.

We finally did our last trail so late we had to knock an hour off the normal time for covering the 3.8 miles. Over 15 miles covered today and we are both slightly weary.