Chapter 14: Oceans of Théxar

"Water is the blood of Théxar. The oceans are its heart, the rivers are its arteries, the clouds are its lungs. As long as the water moves, the planet is alive." — From the "Book of the Cycle", sacred text of Xha'Ruun

Related sections: → see [Ch.03, "Planet Théxar"], → see [Ch.12, "Geological Evolution"], → see [Ch.13, "Continents"] Key principle: 67% of Théxar's surface is covered by water, forming a global hydrological system — two oceans, five seas, an extensive river network. This system determines the climate, provides resources, and is the habitat of another sapient species — the Moryn.

Introduction

Water is a fundamental factor of Théxar's habitability. 67% of the planet's surface is covered by ocean — with one important distinction: Théxar has two oceans, not one global one. The system of continents and islands separating them creates complex circulation, unique to each water area.

Théxar's hydrosphere is not simply "water around land." It is a complex dynamic system, including:

• Two oceans with different circulation and salinity regimes
• Five seas — each with its own hydrological profile
• An extensive river network with a total length of ~244,000 mo
• The cryosphere — polar ice caps covering 0.34 million mo²
• Subglacial lakes at the south pole (at least 4 major ones)
• A system of hydrothermal vents on the ocean floor

In this chapter we examine the oceans and seas of Théxar — their physical parameters, circulation, ecosystems, and significance for civilization. Rivers, lakes, and the cryosphere are covered separately. → see [Ch.XX, "Rivers and Lakes"]

14.1 Ocean Thalas — Northern

PROFILE: Ocean Thalas

Parameter	Value
Average depth	4,490 sha
Maximum depth	10,270 sha
Surface T (equator)	57.0°X
Surface T (polar)	44.0°X
Salinity	3.5%
pH	7.9–8.1

Ocean Thalas is the largest body of water on the planet, occupying most of the Northern Hemisphere. Its name comes from the ancient root thal- ("deep", "depth"). The average temperature is higher than that of the southern ocean, due to:

• Seasonal heating depends on orbital geometry; mean ocean temperature also depends on heat transport and storage.
• A system of warm currents transporting equatorial heat to the pole
• The configuration of continents, creating a heat "reservoir" effect between Kharak and Rhuval

14.1.1 Bathymetry

The floor of Ocean Thalas is divided into three main provinces:

Khar-Tor Trench — the deepest point of Ocean Thalas (10,270 sha), located in the subduction zone off the western coast of Kharak. → see [Ch.12, "Plate Tectonics"]

14.1.2 Circulation

Fig. 14.1. Circulation diagram of Ocean Thalas.

Main currents of Thalas:

• Tor Current (warm) — originates in the equatorial zone off the southern coast of Kharak, moves northwest along the continent, transporting ~32 Sv (1 Sv = Sverdrup, 10⁶ m³/s). Thanks to this current, the northern regions of Kharak are 5.4–8.2°X warmer than would be expected at their latitude.
• Thalas Current (cold) — return current along the western coast of Rhuval, carrying cold waters from southern latitudes toward the equator.
• Thalas Circumpolar Current — circles the northern polar cap clockwise.

14.2 Ocean Gharra — Southern

PROFILE: Ocean Gharra

Parameter	Value
Average depth	3,840 sha
Maximum depth	12,010 sha
Surface T (equator)	54.9°X
Surface T (polar)	44.1°X
Salinity	3.3%
pH	7.8–8.2

Ocean Gharra is the southern ocean of Théxar. Its name is linked to the impact basin of the Gharra Sea, formed ~5.5 billion cycles ago. → see [Ch.12, "Planet Formation"]

14.2.1 Deepest Point

Thash Trench (12,010 sha) — the deepest point on the planet, located at the boundary of the Rhuval and Gharra plates in a subduction zone.

At the bottom of the Thash Trench, a unique isolated ecosystem based on chemosynthesis exists. The pressure here reaches ~952 tyazh, water temperature — 46.6°X (1.6°X higher than in similar deep-sea trenches, due to geothermal flow).

14.2.2 Circulation

The circulation of Ocean Gharra is determined by two factors: strong wind forcing ("roaring forties" of the southern latitudes) and a deep-water current from Thalas through the Ven-Khal Strait.

• Gharra Circumpolar Current — a powerful current circling Vexar from the south. Creates a ring barrier, partially isolating the southern waters.
• Ven-Khal Current — a cold deep-water current connecting Thalas and Gharra through the strait between Rhuval and Vexar.
• Deep-water upwelling — off the western coast of Vexar, caused by diverging currents. Provides upwelling of nutrient-rich deep waters.

14.3 Seas

The five seas of Théxar are partially isolated water areas with their own hydrological regimes.

TABLE 14.1: Seas of Théxar

Sea	Area (mo²)	Avg. depth (sha)	Connection to ocean	Feature
Serrin	132,200	1,463	Thalas (south)	Warm, shallow, between southern Kharak and northern Rhuval
Irkhen	115,700	2,195	Thalas (east)	Stormy, archipelago, cultural crossroads
Thash	78,500	2,927	Gharra (west)	Deep-water, contains Thash Trench
Ven-Khal	62,000	1,098	Gharra → Thalas	Strait sea, connects two oceans
Koss	40,500	732	Gharra (south)	Cold, polar, rich in krill

Sea Serrin

The warmest and most productive sea of Théxar. Located between the southern coast of Kharak and the northern coast of Rhuval. Average surface temperature 58.1°X. The sea is named after the planet's largest satellite — Serrin, whose gravitational influence determines the tides.

The biological productivity of the Serrin Sea is the highest on the planet (≈320 g C/m²/year), due to:

• Constant inflow of nutrients from Kharak's rivers (especially Thar)
• A well-developed shelf (average depth 1,463 sha)
• Stable upwelling along both coasts
• Optimal temperature regime (57.0–59.2°X)

Sea Irkhen

A stormy sea between Kharak and Rhuval, named after the Irkhen Archipelago. Characterized by strong tidal currents (especially in narrow straits) and frequent storms (more than 60 days per year with waves >3.7 sha). The most important maritime trade routes connecting Kharak and Rhuval are located here.

Sea Ven-Khal

The only sea connecting two oceans. The Ven-Khal Strait (85 mo at its narrowest point) is the planet's most important maritime corridor. Water exchange between Thalas and Gharra occurs through it, making its hydrological regime transitional.

KEY FACT

Approximately 8% of the total water exchange between Théxar's oceans passes through the Ven-Khal Strait. This water exchange is critically important for the planet's thermohaline circulation.

14.4 Ocean Currents and Thermohaline Circulation

14.4.1 Global Conveyor

Théxar has a global thermohaline circulation — an "oceanic conveyor" redistributing heat between the equator and the poles.

Fig. 14.2. Diagram of Théxar's global thermohaline circulation.

Circulation stages:

1. Warm water on the surface of Thalas moves north (Tor Current), releasing heat to the atmosphere
2. Cooled, denser water sinks in the northern latitudes of Thalas (deep convection)
3. The deep current moves south, passing through the Ven-Khal Strait into Ocean Gharra
4. In Ocean Gharra, part of the deep water rises (upwelling), closing the cycle

Parameters of Théxar's thermohaline circulation:

Théxar's slower circulation (full cycle 2.5× longer) is a consequence of weaker wind forcing and a smaller salinity gradient between water areas.

14.4.2 Tides

Théxar's tidal system is determined by two satellites — Serrin and Thel:

The stated mean tidal height is 1.2 sha. Local height depends on coastline and basin geometry.

14.5 Marine Ecosystems

14.5.1 Main Zones

By depth and illumination, Théxar's marine ecosystems are divided into classic zones:

14.5.2 Coral Reefs

Théxar's coral ecosystems differ in two key parameters:

• Biomineralization: instead of calcite (CaCO₃), a silicon-calcium composite is used, more resistant to dissolution in the less alkaline environment of Ocean Gharra (pH 7.8)
• Symbiosis: reef-building organisms enter symbiosis not only with photosynthesizing algae but also with chemoautotrophic bacteria, allowing reefs to thrive at greater depths

The largest reef system is the Great Thalas Reef (extending ~650 mo along the southern coast of Kharak).

14.5.3 Hydrothermal Vents

At least 12 hydrothermal vent fields ("black smokers") have been discovered on the floor of both Théxar's oceans:

Vent ecosystems are based on H₂S chemosynthesis — using a 6-letter genetic code, which provides significantly greater biochemical diversity. → see [Ch.04, "Biochemistry"]

14.6 Ocean Resources

TABLE 14.2: Main ocean resources

Resource	Reserves	Extraction method	Application
Fish and seafood	24 million t/year (sustainable catch)	Fishing fleet	Food
Bioactive substances	Virtually unlimited	Cultures + extraction	Pharmaceuticals
Oil and gas (shelf)	18 billion t o.e.	Platforms	Energy, chemicals
Polymetallic nodules	120 billion t	Deep-sea mining	Metallurgy
Gas hydrates (methane)	~42 mo³	Experimental	Potential fuel
REE (from brines)	High	Evaporation	High technology

14.6.1 Deep-Sea Mining

Théxar’s civilization has developed industrial deep-sea mining of polymetallic nodules at depths up to 7,317 sha. Extraction is carried out by specialized automatic stations using bio-optical computers for navigation in conditions of complete darkness and high pressure.

14.6.2 Ocean Energy

14.7 Ocean and Civilization

14.7.1 Maritime Trade

Despite developed maglev transport and aviation, maritime transport remains the primary means of freight transportation on Théxar, especially for heavy and liquid cargo. Largest ports:

14.7.2 Moryn — Oceanic Intelligence

Théxar's oceans are the habitat of the Moryn, the planet's second intelligent species. → see [Ch.05, "Intelligent Species"]

The Moryn primarily inhabit the deep-water zones of Ocean Gharra, where pressure and temperature are stable. Their civilization is built on bioluminescent communication, hydrothermal energy, and cultivation of deep-sea ecosystems. Contact between the Moryn and the Xha'ri is conducted through special interface stations at depths of 244–610 sha.

14.7.3 Law of Silence and Ocean Protection

In accordance with the Law of Silence, certain ocean zones are declared protected. The largest of these — the Gharra Deep protected zone (0.51 million mo²) — covers the deep-water trenches of the southern ocean, including the habitat of the Moryn. Any industrial activity is prohibited in this zone, and scientific research is strictly regulated.

Chapter Summary

Key takeaways:

1. Théxar has two oceans: Thalas and Gharra, separated by continents.
2. The planet's deepest point is Thash Trench (12,010 sha) in Ocean Gharra.
3. Five seas have unique hydrological regimes — from the warm Serrin to the polar Koss.
4. Thermohaline circulation is 2.5× slower (full cycle ~2,500 years).
5. Marine ecosystems include unique silicon-calcium reefs and deep-water chemosynthesizing communities.
6. The Moryn — an intelligent species inhabiting the deep-water zones of Ocean Gharra.
7. Ocean energy uses tides, waves, currents and thermal gradients; the table gives the listed sectors.

• Ocean Thalas: avg. depth 4,490 sha
• Ocean Gharra: avg. depth 3,840 sha
• Deepest point: 12,010 sha (Thash Trench)
• 5 seas: Serrin, Irkhen, Thash, Ven-Khal, Koss
• Water coverage: 67%
• Ocean pH: 7.8–8.2
• Average salinity: 3.3–3.5%
• Full cycle of thermohaline circulation: ~2,500 years

Connections to other chapters:

• → see [Ch.03, "Planet Théxar"] — general planet profile
• → see [Ch.05, "Intelligent Species"] — Moryn, oceanic intelligence
• → see [Ch.11, "Ecology"] — marine ecosystems
• → see [Ch.12, "Geological Evolution"] — tectonic basis of ocean basins
• → see [Ch.13, "Continents"] — coastline, ports
• → see [Ch.XX, "Rivers and Lakes"] — river network