Scarlet Bay Prison is an infamous prison complex situated on an island in international waters. Its position over the years it was running allowed it to get away with numerous human rights cases of abuse until the political pressure mounted for governments to pull out of there. Now taken over by a private company offering tours and "Realistic life experiences" of being a prisoner in just such a thing, including living in stone and metal cell, being kept in chains 24/7, having to work in the still-rich iron mines, the complex surrounds and even the various forms of punishments the prisoner endures. And it's currently open for bookings for new voluntary prisoners who seek a new thrill like none other~ They even operate several payment schemes, even a "pay as you go" plan, where you work off your debt in the iron mine. Still, they make it clear up front that there's no getting out with outstanding debt and no cancellations.
They don't tell you just how little the ore is valued in the open market. An average diligent worker can pay off 1.2 days in a 10-hour shift. Of course, not all city-dwellers have the muscle or activity levels to be nearly that productive for their first few weeks until they have built it up, but that doesn't mean they are held to a lower standard; slacking off is quickly punished. Even while in isolation, they still accrue dept. Every week spent not working will take the average worker five weeks to work back up to get to where they were before that punishment alone.