Sails of Hope. Simon Wiesenthal.

Sails of Hope: The Secret Mission of Christopher Columbus.

Simon Wiesenthal.
Macmillan: 1973.

A fast and interesting read which proposes that Columbus was either a converted Jew, a crypto-Jew (marrano), or came from a family of conversos. Wiesenthal is never foolish (or confident) enough to make a solid claim, and indeed, his scholarship is definitely at an interested amateur level, but he draws on the research of others and does two things: he shows that Columbus being Jewish or of Jewish descent is an Occam's razor for many of the unanswered questions about him, and he also poses a few questions that lead one to accept his idea, at least as a working hypothesis.

The bulk of the book, actually, deals with the plight, importance, and fate of Jews in Spain; this in itself makes for interesting reading.