Anthony Hurford has been living in Bukit Lawang for the last two months doing volunteer work on a research project. He contacted BBC News Online by e-mail to describe the devastation caused by Monday's flash flood.
On the drive up to Bukit Lawang on Monday we saw lots of ambulances and unofficial vehicles, police and army trucks being used as ambulances.
The road crosses the river a number of times on the drive up and the devastation was already clear.
Huge tree-trunks had been piled up along the edge of the river and it was clear to us how high the water had been from mud marks on houses.
The residents of Bukit Lawang are stunned
When we got to Bukit Lawang, Indonesian friends of ours ran to us crying and saying they'd lost their houses, so we comforted them and assured them we'd do all we could to help.
The scene at the mosque on the edge of town was chaotic. A few large sheets of paper displayed names of the confirmed dead and the grounds of the mosque were overflowing with people.
We didn't get close enough to see, but assumed the dead were being kept there.
A walk up the river is a walk into an entirely new place. There simply is no village
We moved on up towards the town.
Usually the bus would take you right in, but there was no "in". The edge of the town was now marked by a bus turned sideways. On the other side were, again, huge piles of trees mixed with personal belongings, parts of houses and lots of mud. The area was unrecognisable.
The river has changed its course and now flows where the right hand bank supported shops and businesses. The left hand bank still supports those guesthouses furthest from the river, as it was, but ground level is now up to window level and most buildings are irreparably damaged.
A massive pile, maybe half the size of a football pitch, of huge tree trunks, branches, wood, personal belongings and the odd tin roof is caught in a corner against rock formations which used to shelter an 'acoustic cave' cafe.
A walk up the river is a walk into an entirely new place.
There simply is no village. Few buildings which were lucky enough to be high up the right bank have survived unscathed, but anything anywhere near the river is gone. It's a beach now.
The army has been spending two days hauling people across the river by a pulley system. They laugh and joke with each other as the locals stand and stare
The orang-utan rehab centre looks to be in bad shape, but those orang-utans still in quarantine cages are said to be still alive - we could only see one of them moving around.
People are walking around stunned. The army has been spending two days hauling people across the river by a pulley system.
They laugh and joke with each other as the locals stand and stare.
Starting from scratch
It is impossible to imagine whether they will want to start again. These people now have nothing at all. There's no insurance here.
They are resourceful people, and I heard that on Monday morning people were already carving their names in logs, earmarking them for construction of new homes and businesses.
But the tourism industry has already suffered massively from other events in Indonesia. They have no savings with which to reconstruct.
Once the area is cleared, which will undoubtedly take months and require the army and special forces guys to stop sitting around and start moving the rubble, people will be able to get on with building.
For now they are sheltered in public buildings on the edge of town, or else the tourism industry workers, jungle guides and restaurant staff have returned to their home villages and families.