Parque Nacional Volcán Tenorio

Saturday’s activity was a visit to the Tenorio Volcano National Park. Our internet research suggested that the road up from Bijagua would be very bumpy and suitable for 4WD vehicles only but this turned out to be completely wrong; they’ve clearly been doing a lot of work on the road recently. It’s now a really good gravel surface and they’re slowly putting concrete down on top. It just goes to show that you can’t believe everything you read online; things do change.

The trail through the National Park started off concrete, then went to gravel, then rocks and mud later. It was a single path there-and-back, though there are suggestions online that it may sometimes be possible (depending on weather?) / may have been possible in the past to make it into a loop. Anyway, it was a lovely walk through a tropical forest, the highlight being the Rio Celeste (Sky-Blue River).

Why the blue colour? Well, apparently it’s to do with something called Mie Scattering. Two clear streams join, one from the left in the photo below and one from straight ahead, under the fallen branch:

The stream on the left carries aluminisilicate particles and is alkali. The stream it mixes with is slightly acidic and the change in pH causes the particles to grow by aggregation (clumping together to us plebs). Some are deposited to cause the white “stripe” in the photo; the others are carried along in the water and scatter light to produce the bright blue colour.

A distinct whiff of sulphur from gases bubbling up in one place reminded us that we were on a volcano:

More pics from the walk:

Our first wildlife for the day was a very odd little creature that managed to attach itself to Mark’s arm. It had a very weird gait. From being pretty flat it would bring its back feet up to meet its front feet, turning itself into a little loop, then it would move its front feet forward to stretch itself out again.. and so on.

Very odd…. We’ve got no idea what it was….

We also saw some crested guan:

Back at the hotel, there was no sign of the cockroach but just before dusk a huuuge moth flew in through our (open) door. I’ve never seen one anything like that huge. Mark saw a dark flash and thought it was a bird…. Luckily we managed to shepherd it outside again and shut the door.