The realm is so vast that other undersea civilizations can exist without ever needing to interact with Rebmankind except in passing, although some have chosen to do so on a more diplomatic basis. There is an understanding, however, that all of these independent communities exist by the good will or disinterest of the Sea's Chosen. Escalating conflicts near Rebman holdings or encroaching on territory deemed of interest to the Crown will invariably result in military action.
Gailes - Human upper-half, octopus lower-half. These ten-limbed hybrids prefer to communicate visually, chromatically, rather than vocally. The population can be found amongst the steppe fissures southeast of Rebma City, beyond the great kelp forest. As ancient allies of the Tritons, Gaile delegations travel to and from The Sunken City two or three times a year, though for what purpose is not clear to observers. Their impressive camouflage abilities help them evade notice if need be, avoiding confrontation wherever possible.
Chthytes - Squid upper-half, human lower-half. Warlike imperialist nation from the abyssal plains of the southern rim, with a startling reproductive rate. The population bubbles over every few years and mounts an attack against an adjacent civilization, most recently the Kelpies of It'rla. They occupy the territory and decimate the defending population with ravenous swarms of their 'failed' offspring, Chthonids. Concepts of mercy and honor are unknown to them in battle. The Rebman military has been able to check the population growth by intercepting the marauding forces at war, but long-term plans must include seeking their bases in the Deeps.
Fishmen - Fish with human limbs, with oversized classic fishheads and jellied round eyes, may look more stoned than stalwart. However, these fast-spawning hybrids have been pressed to fill the ranks of deep civilization armies due to their love for a good strong overlord to boss them around and give their lives purpose. Their dorsal fins are equipped with neural toxin-delivering spines. Their limbs are muscular though the legs are disproportionately stubby and scuttling.
Serpentines - A lost civilization of intelligent seamonsters with shifting abilities and mastery over Sea magics. Only a few individuals are known to exist.
Kelpies - Horse front-half, fish back-half. The population is teetering on the brink of extinction after war with the Chthytes, and the surviving Kelpie Oshan has entrusted Rebma with the protection and rearing of seven hatchlings. The Lord Regent has ordered rebuilding in It'rla to support the species in their duties as watchguards over the legendary slumber of The Great Mother, a massive Hippocampus.
Deepwalkers - Subrebmans with advanced fishy features living on the Sea bed between -5000 and -8000 feet. Gawky and timid, they would never claim ties with the elegant, even-featured Rebmans, though some scholars speculate that they are ancestral throwbacks, or.. perhaps.. the future of Rebma as it expands into the Deeps. The webbed digits, scaled skin patches, large poached-egg eyes, spiny humpbacks, and tail nubs, all these things could be in store for the pureblood Rebman stock unless they dilute!
Nereids - Sea Nymphs and Sea Fae, these are female folk of pure magic who embody the beauty and caprice of the Sea. They do not necessarily recognize Lir as the One True God, but claim that they helped him unify the Rebman ancestors long ago. They can pop up at any time in various guises (wee wisps, maidens, old crones, with emotional wisdom correlating to apparent age), to 'help' travellers and people of interest. In spite of their immortality, they are not infinite. And there are those out there who find them quite tasty.
Jellies - Intelligent jellyfish horde. Approaching critical mass, the collective gets rather unexpectedly brainy… it is undecided whether this is a good or bad thing. They are currently friendly-behaving towards Rebmans.
It'rlaeans - Scattered race of one-eyed humanoids, they once held a prosperous, mighty undersea kingdom, and were close allies with the Kelpies. Fortunes turned upon the arrogance of one Prince, or so the legend states.
Coelacines - Deathless stone race, found in the neglected ruins of old civilizations. Discoverable through RP.
There is still more room for undiscovered races in the unexplored areas of Rebma, as well as many unique individuals who add colour to the realm. Please do discuss your ideas with the propcos.