Here's the submarine description - an information sidebar for players. Needless to say the information for referees isn't quite the same in all respects...
The SILGRS (Smithsonian Institution Low-Gravity Research Submarine) is designed for use in Ceres and any other asteroids found to contain liquid water. Since it operates in very low gravity where ballast tanks would be ineffective, its motion is controlled entirely by its propellers and fins.
Powered by a sodium-fuelled atomic blast, the SILGRS has four steerable electric propellers for a cruising speed of 15-20 KPH; in an emergency the atomic blast can be run at full power, for estimated speeds of 30-60 KPH. However, instrumentation and sonic obstacle detection may be ineffective at higher speeds, and the steering function of the electric engines will be impaired. The hull has been rated for vacuum and for depths to 100 KM within Ceres.
There is accommodation for up to eight occupants including the pilot, navigator / radio operator and engineer; oxygen is supplied via electrolysis, with carbon dioxide and other waste gases vented automatically, so life support is not a limiting factor. Scientific equipment includes cameras, sampling ports, a microscope, blue / UV spotlight, etc.
Note: While the SILGRS has not been designed as a spacecraft, the atomic blast is capable of attaining orbital velocity from Ceres – this may be useful if it is necessary to surface at a point remote from the base camp. However, there is no landing system and attitude control in vacuum is VERY limited, the occupants will have to wait for rescue. This procedure should only be undertaken in an emergency.