To get to the underground sea of Hueco Mundo, you would first have to find the staircase down into it from the very lowest floor in Las Noches. While this is not difficult, it is deceptive as the staircase to it goes up before going down, mainly to throw idiots off.

The walk down is dark, nothing illuminates the staircase down into the deepest darkest parts of Hueco Mundo, the air is intensely cold as you go down, then, as you come nearer to the end it begins to heat up. Not burning hot, although the cold might convince you so, but hot enough that you're not going to want to be overdressed.

There's a door, a rather ordinary door and then, you are in Chara's lair.

Since the Shinigami were last down it, there have been a few changes. There is still the red sofa, green glass table and purple chair that used to be there but otherwise it's completely different. All the surfaces seem to be made of pulsating, living flesh. The entire room is alive and breathing and above the room, there is one huge eye watching everything. It seems to never stop staring, you could probably just stab it shut however. Running at the top of the room are three large metal pipes, coming from the wall of flesh, they each have a piece of glass on the side, coloured yellow, showing that the liquid is flowing through them properly.

To the left is another room, Chara's 'laboratory', although it's not really much of a lab, more a testing facility. Instead of the large metal containers, there are now a set of twelve containers made of the flesh that makes up the walls, as well as some organs on each of the containers which also pulsate and move.

There are more eyes here, about thirty, they all observe the people in the room and it's quite likely that your escape would not go undetected.

The yellow sea is still in the same place as usual, that is, it is just across from the lab and the lab is opened up onto it, but there's a difference from last time, not only does it seem to have tides and waves but there also seems to be a breeze, a hot one. It's of course not a breeze, as you could tell by listening. It's actually something breathing further away, at sea, the room itself has to breathe obviously.

It is never safe to be here alone. The room itself is capable of working on it's own and killing you. It's brain is located at the far reaches of the sea and you would have a great deal of trouble going that far in a single day. The sea is also very very deep, trying to go across it without a boat is not clever at all.

In one of the containers in the laboratory, the only one always filled, is a clone of Chara. It's his fail-safe for incase he dies and will come back to life itself. To kill Chara you have to destroy this place too as it, being Chara, just gigantic and spread out, is capable of over time, restoring the original.

The room is permanently in Resurrecion and has all the powers of a usual Arrancar, so the walls are like iron. It's a difficult place to destroy.