The Black Hole

The Black Hole was Jagex's early punishment system back on RuneScape Classic. It existed throughout most of 2001 but was removed by December of that year.

Function
The Black Hole was a place where players who were found to be behaving badly were sent into. It was essentially a place of total blackness where the players could not move or teleport out of. Players were sent there for an indefinite period of time before being taken out. The Black Hole consisted of the void space outside the programmed areas. Players who were sent into the Black Hole would have their law runes removed to prevent them from teleporting out.

The Black Hole Experience
See Disk of Returning.

A lot of players began deliberately misbehaving to see what it was like to be inside of the black hole, so eventually Andrew Gower programmed a clone of the Black Hole, dubbed "The Black Hole Experience". Players went into the western section of the Dwarven mine (to where Boot the Dwarf can be found on present-day RuneScape) and purchased a Disk of Returning from a dwarf named Thordur for 10 coins. Once a player had a disk in their inventory they were allowed to go down the ladder into the mock black hole.

The Black Hole Experience was eventually removed, along with the real thing, due to players attempting to scam one another by claiming that "something really cool" would happen if players dropped the disk while in the hole, effectively trapping them until Jagex rescued them. This was before the game system could prevent players from dropping certain items, and almost 6 years before the Lumbridge Home Port spell was added to the game.

Postbag from the Hedge #6 gives the storyline reason of why the Black Hole was removed.

In RuneScape'' Classic there exists some bugs that allow the player to walk through certain walls and into the void. One early player, M_Oldfield, was known to be sent to the Hole for macro use, and was the only known player to escape from the Hole.