By Duncan Kennedy BBC News, Mexico

Millions of migrants have crossed illegally from Mexico into the United States. Their experience could hardly be more real. But now at a controversial theme park in Mexico, tourists can pretend to be an illegal migrant.

Tourists pretend to be illegal migrants who are chased and shot

Torch, check. Heavy boots, check. Willingness to hide under bushes, check. Ability to see in the dark, an advantage.

Preparation for what, you might think? A hike across Dartmoor? Try a night out in a theme park.

But when I say theme park, do not think Alton Towers or Disneyland. Think, instead, illegal migrants. Because now you can pretend to be an illegal migrant at a theme park in Mexico.

Mexican migrants

They come to the Eco Alberto Park to be shot at, chased and to wade through fast-flowing rivers.

I myself developed a certain connection with one such river, but more on that later.

Eco Alberto Park is about 700 miles from the border near Ixmiquilpan

For the equivalent of $19.50 (£10), you can spend a night living like the millions of Mexicans who actually risked their lives crossing into the United States.

Except that here, the park is nowhere near the border and most people who turn up are about as likely to cross illegally into the United States as President George W Bush is to tunnel his way into Mexico.

The evening begins with a blood-curdling shout by Poncho, our balaclava-wearing head guide.

"Vamos! Let's go!" With that we all sprint off into the night. And I do mean night. It is inky dark and icy cold. This is, after all, the desert.

But do not conjure up images of Lawrence of Arabia strolling around pristine sand dunes. No, this is rugged, unforgiving terrain.

A kind of game

I came to give solidarity with real migrants. I feel it could be like this A tourist at Eco Alberto Park

The plan is simple. We are the migrants and we are being chased by fake border patrols.

Within 30 seconds, I was hurtling down a hill.

Within 40 seconds I was lying at the bottom of that hill, having tripped.

And within 50 seconds, I was being knocked senseless by a woman who had also lost her footing, but who had skilfully directed her soft-landing onto me.

A bit further on, the real heavy stuff began. The shooting, I mean.

They had assured us that the fake border guards were using blanks, but they certainly sounded real.

"Come out, we know you are there," the guards taunt us, as we crouch in our bushes.

More shots, more shouting.

You know it is a kind of game, but all of a sudden it takes on a realism I had not expected.

Bang! And yet another shot and yet another shout. Sirens too.

We are told by Poncho to stand up. It is to witness an arrest.

The migrants that have been 'captured' are taken away

Yes, already for two of our group, the evening is over. They have been "captured".

The luckless pair are then led off into the night, never, by us at least, to be seen again.

Harbouring doubts

I use the moment to snatch a conversation with our group.

"I came to give solidarity with real migrants," one man told me. "I feel it could be like this".

Soon, we are off again. During the next sprint, I glimpsed one woman on the ground nursing a blood-stained knee.

Remember, this is for tourists.

We cross fences, tackle rickety bridges and bend double to make our way through tunnels.

Amnesty International has criticised the whole thing as trivialising the lives of real migrants. But Poncho does not see it like that.

A staged death is intended to heighten the drama

"It is serious," he says, "and it is our way of paying homage to those who seek a better life in America."

Five hours had now passed. This was an evening of hunting, fishing and shooting, without the fishing.

We came to a wood. And in the wood lay... that fast-flowing river.

For several minutes a man in front of me had sneakily been using his torch. It was my visual lifeline.

But then it happened. Suddenly, he switched off his light.

He went left, I went right and straight into the fast-flowing river awaiting me.

Losing my grip

For the first few moments, I thought it was a large puddle. But as the momentum drew me in, so the water level rose. And rose.

And with the depth came the speed.

In a Florida theme park, they might be tempted to re-name the whole thing 'Migrant Mountain'

Before I knew it, I was swept off my feet. Luckily, there was a small bridge. I clung to it, but by now my feet were being dragged away.

This was not so much a bridge over troubled waters, as legs stuck under troubled waters. My grip was loosening.

The guides realised what had happened and came to me.

One grabbed my hand, another tried to grab my jacket.

They pulled, I pulled. But the river pulled harder.

I simply could not swing my legs out, the force of the water was so great.

And something approaching panic was beginning to set in.

Another couple of guides appeared. Thankfully, it made the difference.

Four men dragged me to safety.

Dripping wet, I thought, what if I had been a small child? I would never have survived.

For me, the evening had been real. I still harboured doubts about whether this was suitable adventure material for paying customers.

In a Florida theme park, they might be tempted to re-name the whole thing Migrant Mountain.

But here in Mexico, it has an authenticity that one can forgive, unlike its fast-flowing rivers.