Three men on death row for carrying out the 2002 bombings in Bali are supposedly being held in isolation, but Andrew Harding hears how they have been communicating with the outside world from their cells.
More than 200 people were killed in the Bali nightclub bombing
It is not exactly Alcatraz.
A narrow stretch of maybe 300 metres of mud-grey sea water separates the prison island of Nusa Kambangan from the Javanese mainland.
If you stare hard enough across the straits, you can just about make out the occasional sliver of barbed wire in the dense green jungle on the far side.
When I turned up at about 1000, a couple of guards were sitting in a shabby, anonymous little building next to an even scruffier wooden jetty, taking down the names of today's visitors.
After a short wait, a ferry appeared at the jetty and two dozen passengers scrambled on board.
It had taken months of haggling and bureaucracy to get me this far, letters from the Indonesian attorney general and permits and stamps from various ministries and the prison authorities.
And all of it something of a race against the clock.
In March, the Supreme Court had thrown out a final appeal by lawyers representing the Bali bombers.
Mukhlas and Imam Samudra say they will not ask for clemency
In May, the attorney general said the three men would be executed by firing squad on Nusa Kambangan Island.
The deadline seemed to be close.
Now you may well think that men convicted of killing 202 people in a nightclub bombing do not deserve any more publicity. But my aim was not to find out if they were planning some tearful death row apology.
Mukhlas (or Ali Gufron), his younger brother Amrozi and Imam Samudra have made it very clear over the past few months and years that they have no regrets.
A few days ago, Samudra managed to sneak a message out to a local hardline Islamic magazine, in which he said he hoped his death would trigger revenge attacks in Indonesia by al-Qaeda.
No, my interest was in the fact that, even on death row, the bombers seemed to find endless ways to communicate with the outside world.
Stream of propaganda
According to the police, Imam Samudra used a laptop computer that had been smuggled into his cell to help organise a second suicide bomb attack in Bali in 2005.
Amrozi bin Nurhasyim is known as the "smiling bomber"
More recently, the men have continued to send out a steady stream of propaganda - messages calling for violent jihad and even advice about how to avoid detection by the security services when working online.
A few weeks ago, I went to a different jail in the Indonesian capital, Jakarta. There were a dozen or more Islamic militants being held there on lesser terrorism charges.
In a corridor, a gaunt Austrian doing 14 years for drug dealing asked me for a cigarette.
He said the militants here keep to themselves, not like the Bali bombers.
"I used to be in jail with them in Bali," he said. "They were always shouting at people, real strong characters."
Later the guards took me to meet the senior militant there, a solemn, bearded man named Pa Adung. He was chatting on a mobile phone when I first saw him.
"It's allowed," he explained. "I only use it to talk to my wives, to arrange visits and so on." But he did not want me to film him using it.
'It's a picnic'
On the way out, I ran into a Slavic-looking man in the car park. He said he was from a Central Asian consulate and had been visiting one of his countrymen inside.
"What do you think about security?" I asked him.
He scoffed: "It's a picnic for these terrorists. Back home, we put them in a cage even when they are in the court room."
Indonesian prison culture is certainly different. The authorities have made huge progress recently in breaking up militant networks, and convicting terrorist suspects.
But corruption is clearly a problem. "With money," the Austrian in jail told me, "anything is possible in here."
And critics say the bottom line is that the Indonesian government still seems reluctant to clamp down too hard on radical groups, for fear of antagonising much bigger and politically powerful, moderate Islamic parties.
A case in point - there are currently tensions over the Ahmadiya, a small Islamic sect whose members have been attacked and their mosques destroyed. The country's top Muslim council says they are heretics whose religion should be banned.
Although Indonesia's constitution guarantees freedom of religion, the government has just imposed new restrictions on the Ahmadiya.
But back to the Bali bombers. This is the point where I should be describing my encounter with them on death row.
But before we got on the ferry, a message came through from the prison governor.
The rules had changed.
No family or journalists allowed to visit the bombers until further notice. No exceptions.
A sign, perhaps, that they may soon be silenced.
From Our Own Correspondent was broadcast on Saturday 21 June, 2008 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.