Tom and his friends were on an island.
They walked through the island.
They listened and then ran across the island to look down the river.

What is the difference between through and across in this text?
The island is a three dimensional space, so why does it use across to express movement to the river?

  • 1
    It's usual to speak of travelling across a piece of land, regarding it as a two-dimensional surface. Sep 24, 2021 at 7:10
  • 3
    The use of through is similar to Lexico sense 1.2, suggesting a thorough exploration. What did your own research find? Sep 24, 2021 at 7:14
  • This question is related as is this one
    – WS2
    Sep 24, 2021 at 7:33
  • 1
    The second one seems strange by itself. Through the jungle, through the village, through the area even, but through the island…is harder to imagine, I think.
    – KannE
    Sep 24, 2021 at 7:43
  • I'm not sure why you can walk through a park, garden, wilderness, maybe even parking lot, but not through an island. I guess it's just a question of what usage sounds most natural given the verb and noun on either side. Maybe in this context walk through implies getting to the other side, and if you walked through an island you'd end up in the sea.
    – Stuart F
    Sep 24, 2021 at 15:13

2 Answers 2


Across is two-dimensional -- it refers to a motion over landscape or flat area. Crossing the area is going from one side to the other, which assumes boundaries on the area.

Through is three-dimensional -- it refers to a motion that may move in only two dimensions, but which counters obstacles in three dimensions.

Contrast walking across the park and through the park, or across the river and through the river, or across the woods and through the woods.

As for why you can't walk through the island, island is simply not a three-dimensional word. It refers to a bounded island surface surrounded by non-island surface, and there's no third dimension to refer to.

  • 2
    Yes - across a field, but through a forest. Re island - I guess if it were the island of Manhattan, or the island of Singapore - you could walk "through" it - as there is plenty of third dimension there.
    – WS2
    Sep 24, 2021 at 22:24

If we set aside the island bit, across suggests the goal is getting to the other side. Through suggests the goal lies within.

If the bar is in the middle of the restaurant, you walk through the restaurant to get to the bar. If the bar is off to the side of the restaurant, you walk across the restaurant to get to the bar.

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