The sun was already hot when we woke at the crack of dawn next day to get ready for a long drive to Tonle Sap.

This enormous freshwater lake covers 2,700 square kilometres during the dry season. But by the end of the monsoon season, it more than quadruples to around 4,000 square metres. Shaped like a gourd, this body of water seems as big as a sea and large communities live beside it – and on it.

We watched the world go by through the minibus windows; we had seen the same houses on stilts on previous days, though it was always fascinating to see Cambodian life going by – chickens and dogs running about, babies sitting in basins being given their baths, children walking to school, women stoking up fires in the rounded clay ovens in their yards, presumably beginning to prepare the day’s meals. This time though, we watched as the houses on the edge of the road became more and more basic; tiny huts, some of which were in near-derelict state, and children who were not at school, but were in rags and ran about in the dust, barefoot. As we approached the muddy, bumpy road that took us to the lake, the poverty was increasingly evident; some of the huts, rising up on high stilts, were built over refuse dumps. The people we saw seemed to be going about their daily lives all the same, and there were smiling faces. Everywhere, there were communal wells, with signboards stating the names of those that had donated them from all over the world. It looked like a place that was on its way to better things – parts of the road were being rebuilt. But it had some considerable way to go.

We arrived at an inlet from the lake where there were rows of wooden passenger boats, and we clambered with Vong onto one of them, the boatman immediately starting up the engine so that we could chug along the inlet towards the main body of the lake. As we started down the inlet, there were boats with sheds on them, which Vong told us were floating schools. Besides them there was even a floating basketball court. We asked if we could make a donation for a school and the boatman pulled up alongside one so that we could step into it.

Girls and boys, all around the age of nine, were sitting taking a class on Cambodian social studies and the girl I sat next to showed me her exercise book, which showed some traditional Cambodian dance moves. The room was cheerfully decorated with drawings and colourful origami and the kids were just like kids anywhere – all getting up to say “good morning” and “welcome” politely, sitting down studiously then, after a while, as we spoke to the teacher, beginning to whisper and giggle. It seemed a happy place. It was explained to us that now every child had the right to free education, and every child attended school either in the morning or the afternoon – just half a day, so that they could help their families the rest of the time. The desks and chairs, pencils and notebooks, however, were often provided through donations. We hoped our small offering might buy a few extra bits and pieces for them.

We had fun on our brief stop there – we didn’t want to distract the kids from their studies for too long – and as we stepped back onto our boat and started back down towards the main body of the lake, smiling faces and waving hands appeared at the window to send us on our way.

We chugged along the narrow inlet towards open water in heavy two-way floating traffic. Boats had to pass close to one another as the edges of the inlet were still shallow after the long dry season and there was always a danger of the boats running aground.

Suddenly the reed beds disappeared and we were in open water and heading out to what looked like open sea stretching out to the horizon. The sky seemed enormous.

After two days of humid heat it was refreshing to be on the water, the breeze keeping us cool. Another opportunity to cool down – a tiny wooden boat with an engine suddeny zooms alongside us and a little girl of about eight jumps onto our boat clutching a basket of drinks. Her mother keeps up alongside her, holding a small baby with one arm while steering the boat with the other. The little girl won’t get off until we buy a can of drink.

“Vietnamese” says Vong. “Cambodians never sell like this” he says.

Suddenly, ahead of us, we see a whole village on water – one side of the lake was where the Vietnamese lived, said Vong – the other side for the Cambodians. Small boats with washing hung out on lines out the back; dogs at the prow, sniffing the air; a pig in a bamboo enclosure, also on a floating boat. A small garden, complete with large chilli plant, bobbed on polystyrene floats. More floating schools. Glimpses of neat dwellings inside many of the boats; children washing, grandmothers dozing on hammocks, smoke rising from small stove chimneys. Small children propelled themselves along in large round floating basins. Vong told us that these people were lake people who had lived on the water for generations – during the dry season they would live on their boats on the lake, fishing for their livelihoods, the children attending the floating schools, and in the monsoon season they would retreat out of the lake and up to a nearby mountain. The houses on stilts at the edge of the lake were all temporary – they would come back and rebuild them once the wet season was over and the water had receded.

We stopped at a large floating cafe, where there was a small display of the aquatic life of the lake, living specimens caught by the owners and kept in tanks. Eels, dacyllus, catfish, turtles, and even crocodiles.

We spend a good hour or so on the lake before returning back to shore for our drive back. By then, the morning batch of children were leaving school and going home for their lunch. We watched the landscape speed by in reverse – as we got closer to the town of Siem Reap, houses appeared more solid, the odd one with fancy balustrades and elaborate architecture built, said Vong, by Cambodians who had made money from tourist by selling souvenirs.

We were dropped off back at our hotel for a rest before heading back to the Angkor complex to see the last temples on our itinerary. We took refuge from the searing heat by the pool, jumping in now and then to keep cool. I kept thinking about what we had seen by the lake. Yes, people seemed cheerful and happy. Back in London, where people had relatively a great deal more – entitlement to health care, full education, welfare support and access to good sanitation, running water, electricity and communications, people often looked so miserable.

Our break over, Vong came to pick us up again for our last visit back to the temples – until next time. Of the three we visited – Kravan, Banteay Kdei and Ta Prohm, the last was the most extraordinary. I haven’t seen Tomb Raider (featuring Vong’s maman-manquée, Angelina Jolie) but have seen excerpts from it on film review programs. I’d thought the stage sets had been designed using computer graphics. No. Angelina’s backdrop was the very real Ta Prohm, the temple that time forgot. For many centuries it lay hidden and forgotten and gradually the forest completely invaded it, growing up into a vast canopy through roofs, giant roots straddling entire walls, sculptures peering out of the gaps. We wandered through this enchanted place, the searing heat and humidity, along with the loud buzzing of the cicadas and the squawking screeches of the parrots adding to its wild and exotic atmosphere. The place is an ancient ruin, and its beauty has been preserved as it is. It can never be returned to its original state without being torn down and rebuilt from scratch. It is stunning as it is.

Our visit to Ta Prohm was a fitting end to our brief stay in Siem Reap. We would be catching an early morning flight next day to Saigon – officially known as Ho Chi MInh City – in Southern Viettnam. That night, Paul and I said goodbye to the lovely town of Siem Reap by visiting the streetside restaurant that he and I had spotted a couple of days before. We sat at plastic tables, eating delicious noodles and drinking ice cold Angkor Beer, watching the world go by on their scooters and bicycles. We’d loved our brief glimpse of Cambodia – if only we had more than two months to travel – and wondered what adventures Vietnam would offer up to us. We were going to have two weeks to explore. We couldn’t wait.