The One Ring and Númenor

Question

Did Sauron have his great Ring while in Númenor? How did he save it then, while in spirit form?

He ... fell into the abyss. But Sauron was not of mortal flesh, and though he was robbed now of that shape in which he had wrought so great an evil, so that he could never again appear fair to the eyes of Men, yet his spirit arose out of the deep and passed as a shadow and a black wind over the sea, and came back to Middle-earth and to Mordor that was his home. There he took up again his great Ring in Barad-dur...

So it appears that the ring was left in Barad-dur. But since he was planning to be brought in captivity to Númenor, why not bring along his precious (!) Ring, both as an aid in the corruption of the Númenoreans and to avoid that someone took it while unguarded?

Note that in a comment to a previous Silmarillion related question of mine it was stated that he had the great ring on the island but I cannot recall it being mentioned and it seems against the text that I quoted....

PS: This question has the obvious counterpart in the LotR, regarding another Maia who dies and comes back. But in that case it is possible to invoke with good reason the intervention of Eru: this is less plausible in Sauron's case.

Answer 1

"He naturally had the One Ring" (sic) with him at Numenor and carried the Ring back using his Maia powers (a rather funny situation to mentally picture), as answered by Tolkien in one of his letters

Good catch, nonetheless, I never wondered about that before :)

I can't keep myself from imagining some sort of shadow dragging the One Ring centimeter by centimeter on 3000 kilometers of seabed... No wonder Sauron became a bit mean.

Answer 2

He had the ring on Numenor, and Tolkien feels that people shouldn't "boggle" at how his spirit carried it off.

In October of 1958, Tolkien wrote a long letter to Dr Rhona Beare (then a student at Exeter University, responding to a list of twelve questions she sent him on behalf of a group of "fellow-enthusiasts for The Lord of the Rings".

‘Question 2’: How could Ar-Pharazôn defeat Sauron when Sauron had the One Ring?

This question, & its implications, are answered in the ‘Downfall of Númenor’, which is not yet published, but which I cannot set out now. ...
Ar-Pharazôn, as is told in the ‘Downfall’ or Akallabêth, conquered a terrified Sauron’s subjects, not Sauron. Sauron’s personal ‘surrender’ was voluntary and cunning¹: he got free transport to Númenor! He naturally had the One Ring, and so very soon dominated the minds and wills of most of the Númenóreans. (I do not think Ar-Pharazôn knew anything about the One Ring. The Elves kept the matter of the Rings very secret, as long as they could. In any case Ar-Pharazôn was not in communication with them. In the Tale of Years III p. 364 you will find hints of the trouble: ‘the Shadow falls on Númenor’. After Tar-Atanamir (an Elvish name) the next name is Ar-Adûnakhôr a Númenórean name. See p.315. The change of names went with a complete rejection of the Elf-friendship, and of the ‘theological’ teaching the Númenóreans had received from them.)
Sauron was first defeated by a ‘miracle’: a direct action of God the Creator, changing the fashion of the world, when appealed to by Manwë: see III p. 317. Though reduced to ‘a spirit of hatred borne on a dark wind’, I do not think one need boggle at this spirit carrying off the One Ring, upon which his power of dominating minds now largely depended. That Sauron was not himself destroyed in the anger of the One is not my fault: the problem of evil, and its apparent toleration, is a permanent one for all who concern themselves with our world. The indestructibility of spirits with free wills, even by the Creator of them, is also an inevitable feature, if one either believes in their existence, or feigns it in a story.

¹ Note the expression III p. 364 ‘taken as prisoner’.

_{Letter to Rhona Beare, 14 October 1958, Letter of JRR Tolkien #211}

Tolkien does not seem to have ever explained how a spirit could carry a ring, but he explicitly says that it's what happened, so I guess we'll just have to take his word for it that it's possible in his universe.