Columbus commences his journal on the third of August, 1492. He writes every single day, so many of his entries are bland and uneventful. By September the ship has made it to the Sargasso Sea. Before long he's floating in unknown waters. He makes constant notations about the location of the ship and the distance travelled.
As promised to the King and Queen of Spain, Columbus keeps track of exciting discoveries. He logs observations of animals, like dolphins and birds. Although not by any means a scientist, he does his best to keep a neat running list of observations. He demonstrates a marked concern for the sensational rather than the scientific. He does make one truly insightful observation, however; he discovers magnetic declination, which is a phenomenon of location which causes a compass to point to a magnetic north which differs slightly from "true" north or the geographical north pole. Magnetic declination had previously been observed, but Columbus is among the first to record the event.
Columbus also writes about the conditions on board the ship. The farther they travel, the more anxious the crew becomes. Many of them start to doubt the success or safety of their mission, despite being warned of their prospects before the voyage. As Columbus admits, the sailors are given an inaccurate distance travelled each day so as to give them false hope. For every mile or so, they're told it's been like five miles. Unfortunately this only serves to make the crew impatient for arrival when the trip seems to be taking much longer than it should. There is nearly a mutiny.
The climax of the journal occurs when Columbus records spotting a mysterious light on the sea. The next day all three ships harbored on American soil. Still confused, everyone believes that they have arrived in some uninhabited region of India. Finally on October 12th, 1492, they had arrived in America. This is the end of Columbus' journal, although he writes somewhat extensively in other contexts about their discoveries in the New World before returning to Spain.
