Besides the transatlantic track, the other important method for determining the location of Guanahani is the inter-island track, which can be traced either forward (from Guanahani to Cuba) or backward (from Cuba to Guanahani). Given the numerous descriptions of courses, distances, and directions in the log, this method seems more likely to pinpoint the location, and has been by far the method most frequently used by historians. It was common practice among 20th-century historians to refer to the various Bahamian islands visited by Columbus by Roman numerals to avoid confusion: Island I being Guanahani, Island II being the second island visited by Columbus (which he named
Santa María de la Concepción); followed by Island III (named
Fernandina by Columbus) and Island IV (called Samoete by the Indigenous inhabitants and renamed
Isabela by Columbus). Following these four islands, Columbus next visited a string of seven or more islands in a line running north–south (which historians generally agree must be the modern
Ragged Island, Bahamas) before landing on the north coast of Cuba. A successful inter-island track must therefore navigate from Guanahani to the Ragged Islands in a way that fits the descriptions of the log without serious infidelity. Strictly speaking this is impossible, as there are a few places where the log seems to contradict itself.
Island II Leaving Guanahani late on 14 October, Columbus said "I saw so many islands I did not know how to decide which one I would go to first". Aiming for the largest, he estimated its distance by eye at five leagues, while other islands were both nearer and farther than that. He arrived at Island II around noon, delayed by a contrary
marea (usually translated as "tide", although "breeze" is possible), re-estimating the distance as seven leagues rather than five. Island II had a coastline facing Guanahani that ran north–south for five leagues, and another coastline ("which I followed", says Columbus) that ran east–west for more than ten leagues. At this point comes a contentious passage in the log: "And since from this island I saw another larger one to the west, I spread sail to go forward all that day until night, because [otherwise] I would not have been able to reach the western cape of the island". From this it is unclear whether the "western cape" at which Columbus anchored that night was on the island with the five- and ten-league coastlines, or the larger island to the west; in other words, it is unclear whether Columbus was adjacent to one or two islands on 15 October. Those who prefer the two-island interpretation call these Island IIa and Island IIb.
Island III The log gives two descriptions of the sail from Island II to Island III on 16 October: in the first version, Columbus leaves at 10 AM and sails nine leagues east–west to reach Island III; in the second version, Columbus leaves at noon and sails eight leagues "almost east-west" to reach Island III. Columbus also gives somewhat contradictory information on the size of Island III, saying at first (before actually exploring the island) that it "may well be" more than 28 leagues long; but later saying only that "I saw quite 20 leagues of it but it did not end there." But Columbus does give quite detailed information on the coastline of Island III, more so than any other island he visited. On the evening of 16 October, he arrived at a cape where the coastlines ran NNW and SSW (though some scholars see a possible transcription error here). The following morning (17 October) he followed the coast NNW, and when he was two leagues distant from the end (or "the cape") of the island, he found a "wonderful harbor" with a small island in its mouth forming two narrow entrances. Going into the harbor with boats, he found it too shallow for use and put the boats ashore for water instead. Leaving the harbor after two hours, he then sailed northwest (rather than the previous NNW) "so far that I viewed all that part of the island as far as the coast that runs east-west". Thus there are four coastlines described at Island III: from the arrival cape, one coast runs SSW, one runs NNW; following the second coast NNW, Columbus arrived at a harbor; continuing along that coast, the coastline runs NW, and then W. These four coastlines and harbor are an essentially perfect fit with the southern part of
Long Island. Columbus ran into foul weather on the night of 17–18 October and gained sea room to avoid running onto a lee shore. He returned to Island III on the 18th, but the log does not specify where on the island he anchored that night. The following morning, 19 October, he split his fleet to search for the island of Samoete that his kidnapped native guides had told him about.
Island IV Leaving his Island III anchorage at dawn, Columbus sent
Niña SSE and
Santa María SE, while
Pinta was sent "east and southeast" (contrary to the ESE mentioned in some sources). Thus the ships were able to sweep a large area of ocean in search of the island whose position was only vaguely known. The
Santa María herself raised the island before 9 AM, and signalling the other ships to rejoin, Columbus reached Island IV before noon, arriving at the northern point. Columbus describes this point as being surrounded by a reef, with a small island nearby. Columbus's descriptions of Island IV are, at best, confusing. He describes Island IV being "on an east-west course" from Island III (which contradicts his previous description of the fleet's movements in the search), and he also asserts that from the northern point the coast ran west for 12 leagues, to its western cape, Cabo Hermoso. The direction of this coastline running west contradicts both Columbus's own arrival at the island (since he arrived at the north point by sailing east, and did not arrive at Cabo Hermoso first) and his later description of his departure from this northern end of Island IV (as he departed sailing SSW and yet did not run aground). From Cabo Hermoso, Columbus described a "great bight" to the northeast. Further confusing the issue, Columbus then says that he believes Cabo Hermoso is on a separate island from Samoete. The following morning (20 October), he tried to enter the bight in order to circumnavigate the island. That attempt soon proved futile because it was too shallow, and Columbus reversed course and returned to the northern end, awaiting the arrival of the King which his kidnapped native guides had told him about. After two days of fruitless waiting for the King and another day becalmed, Columbus departed from the northern end of Island IV at midnight on 24 October, setting his sights on Cuba, the large island to the south he had been told about. He sailed WSW until dawn on the 24th, then was becalmed again until noon, making scant progress in the afternoon. At some point, he fixed his position at seven leagues southeast of Cape Verde, which he describes as being "in the western part of the southern part" of Island III. From that point, he made two leagues on a doubtful course under a rising wind; then, the morning of 25 October, he made five leagues WSW and another 11 leagues west when they sighted the Ragged Islands, which he called the
Islas de Arena ("Sand Islands") running north–south at a distance of five leagues. ==Candidates==