Undertow Rays
Undertow Rays are the great rays of the Surging Deep. They ride its undertow, the deep currents that carry a swimmer far across the plane, and they rise from it to fold around whoever swims above and pull them down. What the current does not strand, the rays eat.
Appearance
An Undertow Ray is a flat, broad fish wider than a fishing boat is long, its upper side slate-dark and speckled with faint lights like stars seen through deep water, its belly pale. Its wings ripple slowly at the edges. Its long whip of a tail trails a wake of glowing water. Its eyes sit on top of its body, small and black, and its wide mouth lies underneath. It rises without a sound but the hush of displaced water, and the deep creatures' song falls quiet as it passes. In the air it would smell of salt and cold.
Habitat and Range
They live in the deep currents across the plane, singly, and rise towards the surface where currents run close under it: at the edges of the kelp islands and in the channels between them.
Behaviour and Temperament
A ray hunts from below. It glides up under a swimmer, folds its wings around them, and dives into the undertow, carrying its prey down and away. Down there it holds them until they drown in the flow and then feeds. Most of its prey are the plane’s own creatures; travellers, slow and noisy in the water, are easy. A ray that is struck hard will often let go.
Abilities
It can ride the undertow at its strongest, where the plane’s currents run too fast for anything else to swim. It moves with the flow and needs no effort to do it, and it is as much a part of the current as a thing of its own.
Life Cycle
They give birth to live young in the warm currents, where the young feed among the clouds of Bloomspawn. Their lives are long. A dead ray drifts down into the depths and feeds the life of the plane, as everything there does.
Uses and Dangers
The Tidesingers sing to the rays, and a ray that hears their song turns away; travellers who swim with Tidesingers are safe from them. Others learn to swim in company, to stay near the kelp, and to watch for the faint lights rising under them. Rays drag travellers into the very danger the plane’s travel notes warn of: the current that strands one in a distant part of the plane.
Lore and Belief
Travellers tell of a dark shape that "took the sea out from under me" and of companions carried off and found days later, far away, alive and changed. On the Material Plane, sailors near Water-Gates speak of a sea-blanket that wraps a swimmer and drags him under; whether rays have ever come through is not known.
Wreck-divers in the deep straits fear the sea-blanket more than sharks, and say it guards the drowned treasure ships of the old wars.