Melville explained the enchantment in several ways:
Melville's sketches are fascinating. Above all, he conveys the highly negative view that the voyagers of his time mainly held. He refers to various islands with words like these: "woebegone landscape," "a dead desert rock," "grim cliffs," and "one of the most northerly of the group, so solitary, remote, and blank, it looks like No-Man's Land seen off our northern shore."
Indeed, there are seasons when currents quite unaccountable prevail for a great distance round about the total group, and are so strong and irregular as to change a vessel's course against the helm, though sailing at the rate of four or five miles the hour. The difference in the reckonings of navigators produced by these causes, along with the light and variable winds, long nourished a persuasion that there existed two distinct clusters of isles in the parallel of the Encantadas, about a hundred leagues apart. Such was the idea of their earlier visitors, the Buccaneers; and as late as 1750 the charts of that part of the Pacific accorded with the strange delusion. And this apparent fleetingness and unreality of the locality of the isles was most probably one reason for the Spaniards calling them the Encantada, or Enchanted Group.
But ... the modern voyager will be inclined to fancy that the bestowal of this name might have in part originated in that air of spellbound desertness which so significantly invests the isles. Nothing can better suggest the aspect of once living things malignly crumbled from ruddiness into ashes. Apples of Sodom, after touching, seem these isles.
However wavering their place may seem by reason of the currents, they themselves, at least to one upon the shore, appear invariably the same: fixed, cast, glued into the very body of cadaverous death.Nor would the appellation “enchanted” seem misapplied in still another sense. For concerning the peculiar reptile inhabitant of these wilds—whose presence gives the group its second Spanish name, Gallipagos—concerning the tortoises found here, most mariners have long cherished a superstition not more frightful than grotesque. They earnestly believe that all wicked sea officers, more especially commodores and captains, are at death (and in some cases before death) transformed into tortoises, thenceforth dwelling upon these hot aridities, sole solitary lords of Asphaltum.
During our tours of the various islands, I was constantly attempting to grasp and imagine the vast difference in point of view between us modern tourists (on our luxury cruise boat) and the early mariners, often searching for fresh food and water, or a place to repair a storm-damaged ship. Melville creates vivid images for my poor imagination.
I plan to explore more of the words of early observers, attempting to comprehend the differences between their views and mine. I've found a website of reference material here, especially with a compilation of early texts (including Melville's).