 SCP-630 is a 130 meter wide underground glacier and, according to surface sonar scans, at least 12 kilometers long, moving at an estimated 30 meters a year. It is composed of what is theorized to be a mixture of water ice, which is an opaque black and does not reflect any form of visible light or electromagnetic radiation. The leading edge of the glacier is fragile enough to take samples from. However, they have been shown to withstand ambient temperatures of over 1500 degrees Celsius without melting. Temperature probes indicate that the glacier is cooled to about negative 10 degrees Celsius, and any significant melting can only be achieved by a sustained exothermic reaction, with the water molecules within the ice. When melted, SCP-630 reverts to ordinary, slightly impure water and displays a normal reflection absorption spectrum.