Thalassa is a planet in the Spelljammer campaign setting. This size D spherical water body is one of the few water worlds without either an atmosphere or floating land masses.[1]
Overview[]
Thalassa appears as a featureless blue-green sphere from wildspace, and is one of the few water worlds without either an atmosphere or floating land masses. Instead, Thalassa is enveloped by an elastic "skin" or membrane which reseals after something or someone has passed through it. Thalassa also has a one-mile-thick (1.6 kilometer) "mantle" of water that has very different properties from the rest of the planet. This layer of water is highly oxygenated, and is referred to by sages as "oxywater." Air-breathing creatures can breathe oxywater and extract enough oxygen from it to survive. Breathing oxywater is an unpleasant and quite frightening experience, and it takes a significant effort of will to do so.
Creatures extract less oxygen from oxywater than normal, which has various deleterious effects on their abilities. Water-breathing creatures are also able to breathe oxywater, with no disadvantages. Thus Thalassa is virtually the only planet in the universe where both air- and water-breathing creatures can co-exist without the use of magic- to a depth of one mile (1.6 kilometres) from the surface, at least. At depths greater than one mile, Thalassa is composed of normal water. There is a distinct division between oxywater and normal water, known to the inhabitants of Thalassa as the "Layer," and this division is visible as a wavy layer of dust and plankton. Air-breathers who pass through this layer will drown unless they immediately return to the oxywater area, or unless they have access to suitable magic.
The water on Thalassa, both the oxywater and normal water, contains a small amount of dissolved salt. Thus it is neither truly salt nor truly fresh, but a mixture of the two. This means that both saltwater and freshwater creatures can exist on the planet.
Thalassa's rotational axis is exactly perpendicular to its orbital plane, meaning Thalassa has no seasons. The water of Thalassa remains a constant temperature, from the surface right down to the planet's core, and averages a comfortable 75°F (24°C). Rumor suggests that there must be a source of external heat, possibly a planar gate to some hotter plane, at the core of the planet, although the intense pressures at the innermost depths have made any investigation impossible.
There are gentle currents through both the oxywater and normal water, none of them exceeding a couple of knots (3.7 kph) in speed. Currents do not cross the division between oxywater and normal water, so there's no enforced mixing of the two. Since Thalassa has no atmosphere, there's no weather of any kind above its surface.[1]
Inhabitants[]
The oceanic ecosystem of Thalassa teems with life. Virtually every form of aquatic creature has been reported on Thalassa. It's important to note that Thalassa has no solid ground, so creatures which need to live on an ocean floor, such as aquatic elves or vodyanoi, will not be found on the planet. Additionally, there are no aquatic mammals, such as whales or dolphins, native to Thalassa.
The bulk of the planet is home to the larger, and generally more dangerous creatures: giant pelagic sharks like the Megalodon, giant squids, and evil beasts like the kraken. For some reason, these huge creatures rarely, if ever, cross into the oxywater layer, and prefer to remain within the black depths of the planet. The oxywater mantle of Thalassa is home to smaller, less deadly creatures, and is inhabited by a great profusion of fish, many of surpassing beauty. There is also a small number of nixies living in the oxywater mantle. The "Layer" is home to a vast number of plankton species, which form a layer up to 50 feet (15 meters) thick. Creatures on both sides of this barrier use it as a convenient source of food.
The two dominant races on the planet are the sahuagin and the merfolk. No-one truly knows the extent of their populations, but it is though that there are many thousands of each race, spread across the world.[1]
The Sahuagin[]
Sahuagin are by nature cruel and rapacious, and may the gods help anyone unfortunate enough to fall into their grasp. The sahuagin operate in multi-family groups of up to 150 members. Each band claims and defends a territory about 20 miles (32 kilometres) on a side, and rarely extends more than a mile (1.6 kilometres) below the "Layer," and doesn't extend at all above it. Sahuagin bands often stage raids into the oxywater above the "Layer," but these are usually hit-and-run affairs, quickly terminated to avoid counterattacks by the merfolk. Under normal conditions, different bands will not cooperate, and in fact often stage raids into each other's territories.
There are legends, however, that tell of a time centuries ago when a source of great magical power fell into the oxywater mantle of Thalassa. (Unfortunately, the legends don't describe what this object was, although some sages believe it was a spelljamming vessel carrying a stash of powerful magical items.) At this time, four complete bands of sahuagin staged a cooperative raid into the oxywater mantle to acquire this source of power. It was a c1ose fought thing, but the merfolk, who are by nature more cooperative, managed to repel the invasion. There's no reason to believe that the sahuagin might not repeat this kind of raid if the potential gains are great enough to warrant it.[2]
The Merfolk[]
The Merfolk of Thalassa are also organized around multi-family groups. These bands are usually smaller than sahuagin groups, numbering between 50 and 75 members. They are not territorial in the normal sense, but do have an innate understanding of "fish farming" and sound ecological principles. Thus, each band will live in a certain region, and will rarely encroach on the domain of another band. Merfolk are naturally more cooperative than sahuagin, and the continuing raids by the 'sea devils' have enhanced this trait. One merfolk band will automatically come to the aid of another should it fall under attack. This cooperation is probably the sole reason why the sahuagin have been so unsuccessful in defeating their enemies.
The merfolk of Thalassa are more comfortable in the oxywater mantle, and have no territorial ambitions with regard to the normal water below the Layer. This is based on several good reasons. Firstly, the fish that they farm live exclusively above the Layer. Secondly, while the sahuagin that raid above the Layer rarely bring with them sharks and other monsters from the depths, should the merfolk try to conquer the sea devils beneath the Layer, they'd have to fight not only the sahuagin but also monstrous fish and sharks. Thirdly, even when it comes to horrid creatures such as the sahuagin, the merfolk are basically peaceable creatures, and have no stomach for a war of conquest.[2]
Spelljamming[]
The Sahuagin[]
The sahuagin have no concept of spelljamming, as such, and would have no interest in it, other than as a potential source of power in their ongoing raids, even if they were to discover its existence. The merfolk, on the other hand, have learned that spelljamming exists from various explorers who have made planetfall on Thalassa in the past. They even understand a little about how spelljamming vessels operate. However, they have absolutely no interest in leaving their home world.[1]
The Merfolk[]
Over the centuries, the merfolk have become suspicious of strangers, fearing that newcomers to the world might be potential allies of the sahuagin. Thus, they'll treat any explorers with grave distrust until the visitors prove their good intentions. Once the visitors have done so, however, the merfolk will consider them friends and allies. While visitors can become trusted friends, settlers are another story. The merfolk consider the oxywater mantle of Thalassa as theirs, and will do whatever it takes to discourage other creatures who want to make it their permanent home. This discouragement will initially take the form of verbal persuasion, but, if necessary, will quickly escalate into war. So far, there has been no need for the merfolk to forcibly expel an invasion from space, but they're ready to undertake the task if it becomes necessary.[1]
Appendix[]
References[]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Nigel Findley, SJR4 Practical Planetology, 1991, (TSR Inc.), Thalassa section, chapter 4 Water Bodies, pages 25-27
- ↑ 2.0 2.1 Nigel Findley, SJR4 Practical Planetology, 1991, (TSR Inc.), Thalassa section, chapter 4 Water Bodies, page 26