L: I wonder what it means.

D: Rincon de la Vieja? “The Old Lady’s Cranny”.

L: The Old Lady’s WHAT?

D: Sigh. I said Cranny. Cranny as in nook and cranny, or corner.

L: Thank goodness for that. I thought you said….

D: I know what you thought. I didn’t. Obviously.

L: No. Right. Anyway, it should be called “Rincon de las Rainbows.” They’re everywhere!

They drive slowly along empty tarmac lanes skirting the foot of the wooded hillside, under a bright blue sky. Way above, where grey clouds are obscuring the volcano’s peak, it is raining, and the buffeting wind carries a mist of sparkling water droplets. Shimmering rainbows, large and small, spring from the road, from gullies, from valleys, and arch over their heads.

The Parque Nacional Rincon de la Vieja is surprisingly wild. Although less than an hour’s drive from Costa Rica’s second city of Liberia, the roads leading to it are mostly unpaved, and the landscape in between is dry, dusty and empty. There is no town to host visitors when they arrive, just a few isolated hotels and lodges, hidden away in the forest.   There is a feeling of unpredictability about the place – of uncontrolled energy. The perpetually strong winds feed an extensive windfarm on the barren uplands between two volcanic peaks, and the land within the park bubbles with hot springs, boiling mud and sulphurous gases. A number of geothermal plants have been established to capture some of this unharnessed power.

The park is divided into two sectors, each with their own ranger’s station, 10km or so apart. The main one is Pailas, on the north-west edge. They arrive at a building site, crammed with parked cars and buses. A huge white visitor’s centre is half-finished – workmen with bandana-wrapped faces turning their backs to the wind to keep swirling clouds of dust from mouths and eyes. A ranger is manning a tiny wooden hut in the middle of a field.

Ranger: Buenas dias – welcome! Here’s a map. I’m afraid some of the trails are closed for construction. There are two you can do – here and here, both out and back. No, the volcano summit trail has been closed for four years – it’s very active. Every day.

D: Excellent! I like my volcanoes a bit lively.

They choose Las Pailas, a 1½ hour walk through thick woodland, over a rickety chain-link bridge, and out into the open. A maze of half-built concrete paths criss-cross the trail, broken plastic ribbons of “Don’t Cross” tape snapping in the wind. There are whiffs of rotten egg, and a number of muddy pools. The whitish-grey mud is dry in some places, or steaming gently from yellow-crusted fumaroles, but in others is bubbling thickly, gurgling and spitting like an enormous pan of sauce on an over-hot stove. Las Pailas means “Cauldrons”.

D: (happily) Look – read the sign. We could be scalded and gassed at any moment.

He waits eagerly for a catastrophe, but remains unscathed.

At the far end of the trail, they reach a pretty stream, crossed on a wide log. They pause. L bends to wet her hands.

L: Weird! Feel this – the water’s warm.

Their second walk is longer – 2 hours each way – to reach the Cangreja Waterfall.   They check with the ranger that the water will be flowing, despite the dry season, and set off, through deeply shaded woods.

D: I think I’m being bitten by something.

L: Here – put on insect repellent. It’s called “Deep Woods”. It should be perfect.

They stand in the twilight of the forest floor, listening to the wind sweeping through the canopy above, and to the isolated call of an unseen bird. The path ahead is wide and flat, criss-crossed with innumerable tree roots.

D: It should be known as the “Forest of the Stranglers.”

L: Err…why? Are there murderers?

D: No. Well, actually, yes, in a way.

L: Seriously? Have people been strangled in these woods?

D: Not people. But look. A lot of these trees are strangler figs. They grow in dark forests like this, where they need to reach the light fast to survive. It’s clever evolution.   Their saplings sprout half way up trees, from seeds left by bird droppings.

L: That’d give them a good head start on anything growing up from the forest floor.

D: Exactly. The saplings shoot quickly upwards to get their heads into the light, and downwards to get their feet into the ground.

L: Which explains all these damn roots I’ve been tripping over.

D: But all that frantic growing tends to strangle and kill the original tree.

L: Poor tree. That’s a bit evil. Is that why some of the trunks are hollow?

D: Yes, the cavity’s the space left by the dead tree. And see – sometimes the figs grow these great buttress roots, so that when the original tree dies, they don’t just fall over. Ouch. I think I’ve been bitten by something.

L: You can’t have been. You’re covered in bug-spray. It’s psychosomatic.

They walk on, and emerge into open grassland, the path now sloping gently downhill, giving far-reaching views down towards the coast. The strong breeze ensures that even in the midday sun they are not too hot. Occasionally they are “spritzed” with a mist of water blown down from the hilltop.

L: It’s a long way for a waterfall. It’d better be worth it.

D: We’re nearly there. I can hear it.

L: I bet there’s 300 people and no room for us to sit.

D: I can see it. There aren’t 300 people. There are……seven.

A final rocky descent through woodland leads them to a large clear pool fed by a white curtain of water cascading from 40 metres above.

L: It’s absolutely beautiful! Definitely worth the walk.

D wades in. The water is refreshing, but not painfully cold. He swims lazily across, climbs out and stands happily under the fall, which pummels and needles the top of his head. The water is colder here. However, on the other side, in a little corner, a small stream trickles down a boulder and into the pool. The water from this stream is as hot as a bath.

The following morning…

L: Sorry. Not my best choice. But at least we had a bed.

D: Which was too small. You pushed me out.

L: And a bathroom.

D: With no hot water. And bare wires poking out of the shower head. It’s a miracle I wasn’t electrocuted. And dinner was horrid.

L: What are you saying? The pudding was tremendous!

D: There’s nothing tremendous about rice pudding. Unless you’re a very small child.

This morning they are driving to the other Ranger’s Station, at the south-west corner of the park, known as Casona Santa Maria. The 3km track is barely passable in places and they weave their way around boulders and in and out of deep ruts as though on a 4WD obstacle course. Eventually they arrive at a flat manicured grass clearing surrounded by forest. To one side is a dilapidated barn, which is empty apart from a small desk and a filing cabinet in one corner, on top of which are several decomposing snakes in glass jars. A cheerful ranger appears, shakes hands with them, and signs them in.

Ranger: There’s one trail – 3km out, the same back. No, not steep, but it can be a bit slippery in places. Have fun amigos!

They set off along a broad path in the woods. Their first stop is at a waterfall.

L: Gosh – I don’t think we’ll be swimming here!

They admire a torrent of angry white water crashing over a 10 metre drop and into a swirling, frothing pool below.

L: I read somewhere that 32 rivers have their sources in the park. It’s a really important water catchment area for the region, because most of Guanacaste’s so dry.

D: Oh. Fascinating. Can I have the insect repellent? I’m being bitten.

He sprays himself carefully and thoroughly.

Further on, they encounter a large family group, arguing noisily in French.

Teenage boy: We’ve had to turn back. There’s a river to cross and no bridge and our parents wouldn’t let us wade it. You could do it, but you’ll get wet!

On they go.

L: That doesn’t sound right. The ranger would have mentioned it, surely. He just said things might get a bit slippery. They must have taken the wrong path.

D: Umm….Oh.

The broad track stops at a wide, fast flowing river. There is no bridge. Downstream it drops steeply over boulders.

L: I expect this qualifies as “a bit slippery”.

D: It’s not so deep.

L: Let’s wade it then.

In the middle, the current tugs at them, the water swirling around their thighs. They stagger across and out, slipping on wet rocks, and carry on, feet squelching. After a while they stop to wring out their socks and air-dry their feet. Then continue.

D: Oh.

L: Another stream. This one’s smaller though.

She wades straight in and across.

L: Shall we squeeze out our socks again?

D: Yes, but hurry up. If I stand still I get bitten.

L: That’s impossible. You’ve sprayed. You’re imagining it.

Further on, they descend to a wide shallow river bed giving off a strong smell of rotten eggs. Rocks have been arranged to form a cluster of knee-deep hot-tub-sized pools. The water flows in clear and peaty-brown, and out white and silty. They wade across the first pool.

D: Cold.

And into the second.

L: Freaky! It’s properly hot, like a bath. And seriously eggy. Where’s the heat coming from?

They sit in it for a bit, trying to work it out. The third and fourth pools are tepid, fed from the hot pool flowing into them and then cooling. However this pool must be being heated from the ground.

D: Well, we’re sitting on volcanic magma – molten rock.

L: Are we? That doesn’t sound awfully safe.

D: Cold water seeps into the ground, and when it reaches the magma, it’s heated up and pushed upwards and back out. Either as hot water, like here, or as steam like in the fumaroles we saw yesterday.

L: What about mud pots?

D: That just happens when the hot water gets mixed up with mud or clay underground and so breaks through the surface as bubbling hot mud.

L: Have you been reading about volcanoes again?

D: Yes. I like them.

When they get out their skins and swimwear smell of eggs.

On the way back, they detour, following a small meandering path through the forest, promising “cold water pots.” At a deserted clearing edged with dead trees, is a wide muddy area with water trickling through it. The stream is cold, and yet vigorously bubbling away. Here the fumes are heady, nauseating, almost overpowering. They explore, in places finding holes within which the water is boiling fiercely as though from a jacuzzi on full power.

L: I don’t understand. How can the water be bubbling and cold?

D: It looks like a spring – I reckon cold water is emerging from the ground here, but there are volcanic gases escaping too, through the water, making it bubble.

L: What sort of gases? Poisonous ones?

D: Umm… carbon dioxide, and the stink is hydrogen sulphide I think. Which is very bad for you.

L: Oh.

D: We’d probably better go – I think my eyes are melting.

L: I thought you liked your volcanoes a bit lively.

D: I do. But now I’m feeling queasy. And I’m sure I’ve been bitten.

L: Do you think you’ve got a neurological disorder? Maybe your imaginary itches are a form of Tourette’s or OCD. I’ll book you an appointment.

They reach the car.

L: Ah.

D: What?

L: I think I might have been bitten.

D: Ha!

Despite all the insect repellent, they are both covered in swollen red bites.