The Climber, as seen from Simon's field of view when in his seat.

 The Abyssal Climber Rig (ACR), commonly referred to as "The Climber", is the sea elevator between Omicron and Tau along with the Omega Sector, that travels from the main plateau into the abyss.   

The Climber cannot be operated from the Abyss, needing an scheduled arrival/departure from Omicron.