I squatted in the dark, listening to the distant sound of toddler duck quacking disappearing into dead air. I took a couple of deep breaths, felt the damp air filter into my lungs, and rested my flashlight in the trickles of icy water beside my feet. The weak light pointed upwards, highlighting the rich chocolate coloured lava, it's icicle-like drips reaching down towards my back. These perfectly formed lavacicles had once been molten droplets, dripping from the shell of volcanic rock. Now each drip was idle and solid, many hosting a single drop of water on their tip. I attempted to shuffle further down the tunnel. The roof was the height of a small child and the small children with us had slipped through without difficulty. Now in my seventh month of pregnancy, I found the recommended 'walking like a duck' technique near impossible. The information leaflet suggested 'walking like a duck' could help adults negotiate hopelessly low ceilings and compressed walls. But if I was a duck, I was a fat round one, and not designed for thin tunnels. I managed a reasonable squat, and moved forward one step until my stomach hit my knees and I became stuck. I gave up and shuffle-crawled along in the dark, with a certain knowledge that caving isn't a sport designed for expectant mothers.

All squeeze together now

On our family adventure, we had accidentally followed the path of the Ring Of Fire around the world. Several of its' volcanoes had provided interesting stopovers in New Zealand, Samoa, and now The States. In New Zealand, we stood on the top of an active volcano and imagined it blowing; in Samoa we visited a village built on lava and met the people who lived on this inhospitable land, but America's volcanos, craters and lava spattered wastelands were an altogether different experience. By travelling through the US National parks we could follow nature's chain of violence and destruction, a healthy activity for three and four year old boys. The children were fascinated by volcanic explosions and their aftermath. Matthew absorbed every detail and was an expert on rock, lava, and spluttering magma. He continued to enjoy the game of testing whether a stone was pumice by throwing it at his brother. If Cameron didn't cry then it was pumice. If he did then it was rock. We weren't encouraging that game for obvious reasons.

"Time for some caving Cam."
"Don't want to go in a cave Daddy."
"Ah, but this one is called Hopkins Chocolate Cave."
"Why?"
"Well, it was discovered by a man called E Hopkins, and the surface of the lava tube resembles chocolate."
"Does the rock taste like chocolate?"
"Maybe."
"I want to go in the cave. I want to go in the chocolate cave. Will there be M and M's?"

At first glance the National Lava Bed Monument was just a heap of arid and barren volcanic soil, populated only by scrawny grass and bits of shingle, lava and cinders that had been spewed up by the volcano. But the ground held hidden treasures, dark passages and secret caverns. Leaving behind the burning heat of the high desert, we descended into the lava tube. Our body temperatures plunged. It was like jumping into a cold swimming pool on a hot day. The air was damp and smelt like an old cellar.
"Cameron, your feet are minging," Matthew accused his brother.
"Well, your bum is smelly," Cameron replied.

We had taken some time to spell out the rules of caving before entry. "You do what we say, when we say, and if you whinge then we'll leave you in the cave."
Primed to behave, each child clutched a sizeable torch, excited to begin their search for chocolate rock. The beams of light from our torches instantly picked out the velvety rich brown lava, which had been frozen in time as it rippled down the walls, like melted chocolate drizzled on to a cake.
"Is that the chocolate? Can we eat it?" said Cameron.
"No silly, it's just rock. And even if it was bubbling lava you couldn't eat it because it would burn your mouth," advised Matthew.
"Dead right," said Stuart. "When lava pours from a volcano it's very hot. About 1,800 degrees fahrenheit."
"Wow, that sounds hot Dada," said Matthew, pointing his torch at the knobbles of lava.
"Is it hotter than Mummy's bath?" asked Cameron.
"No, it's not that hot, Mum likes her bath really hot," answered Matthew respectfully.
"Is it hotter than Mummy's coffee?"
"Yes, much hotter," said Stuart. Cameron was satisfied, but only for a moment.
"Don't like it here, it's too dark."
"I expect he wants to see the way back," said Matthew, confidently shining his torch behind us into the blackness we had come from. Going back, or at least ascertaining the way back had become an obsession of Cameron's; almost from the first day of our journey.
"Is there chocolate in that way back?" Cam asked.
"No, the man didn't leave any chocolate in there for us," replied his brother.
"Which man Matthew?"
"Mr Hopkins. The man who found the cave. He really liked chocolate."

Matthew searches for Mr Hopkin's chocolate

"Choc…I've found some chocolate." Cameron's mood changed as we stumbled across the bar of Dairy Crunch Stuart had just planted on a rock.
"And I found a pink jellybean," said Matthew, jumping up and down and hitting his head on the tunnel roof. "I think it must be raining jellybeans in here. Isn't that rope lava up there Dad?" He pointed his torch at a particular formation that I'd no knowledge of. I promised myself I'd read up on rope lava when we got out. Matthew then pointed his torch further into the tunnel. "Oh no, we're coming to a low bit, Mum's going to have to walk like a duck, quack quack." The kids laughed and ran ahead as I braced myself for the duck squat. This wasn't dissimilar to childbirth.

"Lava tube caves are formed when the molten rock pours from the volcano. The outer edges and surface of the flow quickly cool and begin to harden, creating an outside shell while the rest of the flow remains hot and fast moving. The flow continues on…."
"Like a river Dad?"
"Yes Matt. And when the eruption stops, and the river of lava drains, the tunnel or tube is left. Some of the tubes here were formed about thirty thousand years ago."
"Is that as old as Mum?"
"It's a bit older than Mum. Now, the next tube on our list is called Skull and Bones cave."
"Why?"
"Because wagon loads of Native American skulls and bones were found lying in there when the cave was first discovered."
"Was it discovered by Mr Hopkins?"
"Yes actually, it was." "Hooray. Mr Hopkins might have left us some skulls and bones Cam."
"Woof woof," said Cameron appreciatively.

Another day, another American State. This time Oregon, and the Lava River Cave, the longest uncollapsed tube in the state, and one of the first to be discovered by settlers in the region.
"Shall we go caving again?" I asked the kids when we turned into the car park.
"Yes. Yes. Jellybeans and chocolate," they cheered. Stuart and I smiled at each other. By turning caving into a game we had hooked them on the sport, at least until it stopped raining jellybeans.
But compared to the atmospheric and deserted lava beds, this tunnel was a public highway, crammed with people holding powerful gaslights provided by the centre. The caves were consequently never properly dark, there were few low ceilings or squashy walls, and we had run out of jellybeans. Cameron wasn't at all impressed by the peanut butter sandwich we left on a rock.
"It's not raining jellybeans in this cave Daddy and I'm tired of walking."
"Raining jellybeans?" A middle aged American couple approached us, their gas lamps burning brightly. "Now that's one thing that nature forgot to organise," said the male half of the couple, who had a belly bigger than mine.
"It rained jellybeans yesterday," challenged Matthew, "near the lava ropes in the chocolate caves."
"Ah, how sweet," said the female half, who also sported an oversized stomach.
"Chocolate caves. Don't they have an active imagination at that age."
Matthew glared at her. "Maybe Mummy will have to walk like a duck later. It's really funny when she gets stuck." The woman glanced at my pregnant belly.
"Too many jellybeans," I told her.
"Is that the way back to England?" asked Cameron, focussing his torch firmly down the tunnel we had just come through.
"Cam, let's go look for the skulls and bones of dead Americans," Matthew said, leading the way through the uneven sandy floor.

Beam me up Cammy