The Landrover zigzags along the battered road, which is deeply furrowed by the heavy rains. We reach a collapsed bridge and our driver, Clare-man David McMahon, has a choice: turn back or try to negotiate the river at its lowest level. Not a man to spurn a challenge, he crosses without incident.
As we crawl in second gear through mile after mile of Cambodia's "killings fields" there is a depressing sameness about the surrounding countryside. Cambodia remains in the throes of social and economic turmoil following a quarter of a century of war and slaughter. The smell of death and decay still hangs in the air.
We pass village after village of makeshift wooden houses with straw roofs, hastily built structures barely able to withstand the elements.
This is the wet season and naked children splash about in the muddy ponds left by the steamy monsoon rains. Few have the privilege of going to school. The elderly sit outside their huts, many watching over their stalls, selling whatever vegetables they have harvested from the fields.
There are no electricity or telephone lines in these communities. Outside one house, batteries are being recharged. This is the village power supply. The batteries will be collected later by local people who will take them home on the back of their bikes. They will provide enough power to burn a light bulb or two for a few nights before they will need to be charged again. A lucky few have a television to power as well.
On the road from Siem Reap in north-west Cambodia to Thmar Pouk district in Banteay Meanchey province, a man is pushed along in tricycle-wheelchair by two of his three children. The youngest, only two years old, is sitting snugly on her father's lap.
We stop to talk. He is one of Cambodia's 35,000 land-mine victims, who lost both his legs near the border in 1985. His wife died last year, leaving him to raise his girls, aged 10, seven and two.
This former soldier fixes radios and bicycles for a living. He has to haul himself out of his chair and crawl along the ground to get into his house. He says his children, who don't go to school, are a big help to him.
Cambodia's slide into destruction began in 1975 when Pol Pot's Khmer Rouge proclaimed a worker-peasant revolutionary state. In a disastrous campaign to achieve anarchy, whole cities were emptied and the population moved to rural work camps. There followed economic chaos, widespread starvation and brutal purges of suspected "counter-revolutionaries". It is estimated that between 1.5 and 2 million people were massacred under the Khmer Rouge regime.
Vietnam invaded Cambodia in 1978, pushing the Khmer Rouge back and installing a puppet government of KR defectors in the renamed People's Republic of Kampuchea (PRK). Non-communist resistance groups emerged and in 1982 the National United Front for an Independent, Neutral, Peaceful and Co-operative Cambodia (FUNCINPEC) fought the PRK government.
In 1987, negotiations for peace began, resulting in the 1991 Paris peace accord. In 1992, the country was renamed the State of Cambodia and the UN began a massive peace-keeping operation.
Elections in 1993 were marred by the murder of political figures and the refusal of the Khmer Rouge to disarm. FUNCINPEC and the Cambodian Peoples government.
Tensions continued however and after the 1998 election, CPP and FUNCINPEC formed a new coalition government. The death of Pol Pot in 1998 and the surrender in December of that year of two Khmer Rouge leaders completed the de facto disappearance of the movement.
The years of conflict have left Cambodia one of the most heavily mined nations in the world. While the country is finally at peace, all of the weapons have not been laid to rest. Millions of land-mines were planted and then forgotten. Their bitter harvest will haunt Cambodia for a long time to come.
Cambodia has the highest rate of amputees in the world - one person in every 250 has lost a limb from mine or ammunition explosions. For every amputee, there is a person who has died from a land-mine. Eighty per cent of land-mine casualties knew they were in a mine site at the time of the accident and 90 per cent of victims are male. Three years after the ending of armed conflict, there is still an average of 26 land-mine accidents recorded in Cambodia every month. There could be many more unrecorded.
Estimates of the number of mines laid in Cambodia range from half a million to six million. No one really knows, because few records or minefield maps were kept during the conflicts, which makes clearance difficult.
In addition to land-mines, there are tens of thousands of unexploded bombs, shells and rockets littered throughout the country.
The Halo (Hazardous Areas Life-Support Organisation) Trust is a British-registered charity specialising in the removal of the debris of war. Founded in 1988, it currently operates in Afghanistan, Angola, Mozambique, Eritrea, Ethiopia, Somaliland, Abkhazia, Nagrno Karabakh, Kosovo and Cambodia. Halo clears an average of 20,000 mines and 170,000 unexploded ordnance (UXO) annually. It started mine clearance in Cambodia in 1992 and has cleared more than 12quare metres of mined land, and destroyed more than 25,000 mines and 20,000 UXOs in that period.
The Irish Government has been part-funding Halo since 1994, and last year donated £260,000 through Ireland Aid. Irish money has allowed Halo to clear the way for thousands of refugees to return to their homes, develop local infrastructure and -funded Halo de-miners cleared 180,000 square metres of land and destroyed 234 land-mines, one anti-tank mine and 93 UXOs.
Halo is unique in that virtually all of its 900 staff is native. One of the two foreigners heading the organisation is 30-year-old David McMahon, deputy programme manager in Cambodia.
In 1993, at the age of 22, McMahon left his job with Clare County Council to manage Concern's transport fleet in Cambodia. "I always wanted to work for Concern and when the opportunity arose I jumped at it," he says.
He then worked for Shell Oil for a year, before joining the Halo Trust. McMahon has worked at every level in Halo and trained as a de-miner. He has moved rapidly through the management structure and was appointed to the number-two job six months ago.
McMahon is a self-confessed Cambodia addict. He loves the country and its people. Five years ago he married a Chinese-Cambodian woman, Bunly, who gave birth to their first baby, Daragh, three months ago. Bunly had her son in Ireland and is one of the few Cambodians holding Irish citizenship.
Chheu Kroam village is in the Thmar Pouk district just a few miles from the Thai border and the famous K5 minebelt. The K5, a strip between one and two kilometres wide along the Cambodian-Thai border is the most heavily mined area in the country and will not be touched by de-mining companies for many years to come. The priority is to clear land for families to resettle first.
This area was the scene of fierce fighting between Khmer Rouge, government, resistance forces and Vietnamese. Most of the mine-laying here was done in 1984 and 1985.
People are now beginning to move back, thanks to Halo, which started mine clearance after a request from the village chief, Em Moem. There had been 20 accidents in the village before clearance work started, with seven people killed and 13 injured.
Two areas in Chheu Kroam, funded by Irish Government grant aid, have been finished and Halo is working on phase three. A sign outside the village proclaims that this project is funded by Ireland.
Since Halo started operations there have been no mine accidents here. Halo staff have been conducting mine-awareness classes for villagers, who attend in huge numbers. So far in phase three, 47 houses have been resettled. Each house has been provided with an outdoor lavatory by a Norwegian aid agency and each householder has been allocated a 40m-by-50m plot of land.
Seventy per cent of the villagers cannot read or write, and there is no school. Most go across the border to Thailand to work as labourers for $1 a day.
Clearing the land is hot, dangerous and meticulous labour. Working in temperatures of up to 100 degrees, de-miners must wear helmets with visors and protective vests. They adhere to strict operational procedures and land is cleared in metre-wide corridors. A de-miner can declare safe up to 50m of land a day. In an area where there is a lot of metal in the ground, the clearance is much slower.
The de-miners start work at 7a.m., take a 10-minute break every 30 minutes and finish work at 3p.m. They work three weeks on and a week off.
McMahon points to a group of 10 houses here in Chheu Kroam which have been built on land not yet cleared by Halo. In this lethal minefield, three children play: Chhean (10), Voeun (six) and Somnang (five). Somnang means "lucky" in English.
The children have been warned of the dangers and try to stick to a path leading from their houses to the safe area. "Our mother and father have told us to be careful," says Chhean.
This morning, his mother is in the forest looking for food. Feeding her family takes precedence over her personal safety. The woods can contain lethal surprises.
"Many of these people feel they don't have any choice. When they haven't money to buy food they go and hunt for it, even if it does mean risking their lives," says McMahon.
In the next few months, the Halo team will de-mine around the houses, giving peace of mind to the families there. "And peace of mind to us as well," says McMahon.
"We do try to discourage families from settling in an area that we have not made safe. But they don't listen. The best we can do in these situations is do some de-mining awareness and ask them not to touch anything that looks suspicious and to keep to pathways and tracks."
Nearby, within the safe zone, a 16-year-old girl is minding her younger brothers and sisters, who are sitting underneath their house sheltering from the sweltering sun. In a couple of hours, the rains will start again.
The young woman explains that her mother is in the woods digging for bamboos and looking for vegetables. Her father is a de-mobilised soldier. They lived in a military base until they moved here.
This has been a bad week. Normally, the young woman travels the few miles across the border into Thailand to work for $1 a day. The only other family income is the $20 a month army pay her father gets. But the army money does not always come. The border has been closed for the past three days, so she has not been able to work and the money has dried up. There is not enough food.
Sman Makera is the Halo Trust location manager for the Banteay Meanchey region and joined in 1992. He is responsible for 270 staff.
He is especially proud to be involved in mine clearance. His mother, father and five of his brothers and sisters were killed by the Khmer Rouge in the 1970s, when he was a little boy. Only Sman and his sister survived.
"My mother knew that the Khmer Rouge were going to get the people in the village. She sent me away to another village to live with a childless couple. My sister was sent somewhere else.
"I remember when my mother said goodbye. She patted me on the head and she was crying. I never saw the face of my mother or father again."
When he was 22, Sman Makera joined the Khmer Rouge for six months, despite what had happened his family. He joined in a moment of madness, he says. "I don't know why I joined. I was young. I regret it now. But I never killed anybody. I was part of a group that destroyed a bridge. My friend joined with me."
In the Halo training centre in Kdep Thmor, new staff are put through their paces and get intensive training before they go out into the field. There is huge competition for jobs. Everywhere he goes, McMahon is approached and asked if he has a job to give. Halo is more than a de-mining agency. It also provides much needed employment for local people. De-miners are paid $150 a month - six times the national average wage - which can support many extended families.
An important part of mine clearance work is making safe explosive material. Pete Williams, a former British army explosives ordnance expert, is holding a training course for Halo staff in Kdep Thmor this month. He is putting a group through their paces, teaching the six stages of disposal: detection, identification, evaluation, the rendering safe procedure, recovery and final disposal. "Cambodia is basically one big minefield and it is important to train de-miners to dispose of items in a safe manner," he says.
What McMahon loves about his job is that he sees immediate results. "With long-term development work, you might not see the fruits of your work for years, in some cases. Here, the results are instant. One week an area is unsafe and the next week it has been cleared by our operations. I feel we really make a difference to people's lives here."
It may be slow, painstaking work, but every square metre that is cleared presents a lifeline to families who are barely surviving. And every square metre of land recovered is another step in the rebuilding of Cambodia.
See The Halo Trust website: www.halotrust.org and anti-land-mine petition site at: www.demon.co.uk/aesop/banmines.htm