Short answers, pulled from the story.
Thetis is a Nereid and sea-goddess who functions as a demiurge creator deity in early hymns. Her name derives from tithemi meaning to set up or establish indicating an original political role. She is the mother of Achilles and shapeshifted into flame water a lioness and a serpent before marrying Peleus.
Worship of Thetis persisted in regions like Laconia well into the second century AD according to Pausanias. The Lacedaemonians worshipped her with utmost reverence during this time while priestesses maintained wooden cult images known as xoanon. Evidence also exists that Persians sacrificed to Thetis at Cape Sepias during the Persian Wars.
Zeus arranged the marriage because a prophecy stated that Thetis's son would become greater than his father. Poseidon joined Zeus in making these arrangements since they feared the outcome of her union with any other god. This decision led to the birth of Achilles whose heel remained vulnerable after she dipped him in the River Styx.
Thetis was worshipped in conservative Laconia where priestesses served before wooden cult images called xoanon. Herodotus noted that Persians sacrificed to Thetis at Cape Sepias identifying her through interpretatio graeca likely as Anahita. A papyrus fragment discovered at Oxyrhynchus reveals hymns from the seventh century BC describing her cosmic role.
One hundred three people were aboard the vessel when it went down and ninety-nine died of carbon monoxide poisoning. The disaster occurred shortly after leaving the dock in Liverpool during 1939 on trials in the River Mersey. An inspection hole allowing a sailor to look into torpedo tubes had been painted over before submersion caused flooding.