The Island Map

Size of the electromagnetic field versus the “time-travel radius”

If the Kahana was initially 46 miles [40 nautical miles] offshore and the crew and equipment were being affected by The Island’s electromagnetic properties, we can infer that the field extends about 50 miles offshore. The boundary of the electromagnetic field is indicated by the yellow line. One would also have to be outside this line in order to “escape” The Island. The Kahana’s approximate initial position is indicated by the K1 marker.

Later, the Kahana moved much closer to the coast of The Island, somewhere in the vicinity of K2, but was not within “the radius” of the phenomenon when The Island moved. This indicates that the time-travel phenomenon is much more localized to The Island, and probably only extends a few miles offshore at most. The time-travel boundary is indicated by the orange line.

Of course, The Island seemed to be fairly selective about who or what actually time-travelled. The helicopter would likely have been inside the radius but didn’t move with The Island. However, Jin would’ve been even further away when he was thrown into the water by the freighter explosion, but he somehow managed to time-travel with The Island. The reason for this may end up being one of those Island mysteries that we never get a definitive answer for.

Here are two articles from LOSTpedia which further explore the phenomena associated with compass bearings and electromagnetism.