The Flude Cauldron is a huge, kettle-shaped depression located twelve kilometers southeast of Plaxton, just east of Trinumvira. It is naturally formed — the likely result of several sinkholes collapsing simultaneously at some point in Caspar's past. The lack of retained water, which would otherwise form a lake, alludes to a network of subterranean soft-spots and porous rock, and a lower water table in this region. Today, it serves as the basis of Union Starport, the second-most trafficked interface on Caspar.