The Dark sea

The Dark Sea is the little known subsurface "Sea" in which the hell islands and Hellpiea are situated. It is made primarily of fine voclanic ash, including pryobloin, an element normally found in Seastone. This acts as a congealant, making the ash behave in an almost liquid manner. In some places, thin veins of cooling lava also appear in the ash.

It can be sailed on by normal ships. However, in deaper levels, the ash is in fact resting on a thin crust of cooled molten rock, which in turn floats on the hotter magma underneath. At these places, the temperature is usually hot enough to set any ordinary ship ablaze, and if it is too heavy and breaks the crust, it will be incinerated instantly. Vessels which travel to these deeper depths need to be designed differently, both to withstand the heat, and to avoid breaking the crust.