1. The weather was so nice when I got to Dokdo.

2. The weather was so nice when I arrived at Dokdo.

3. The weather was so nice when I arrived in Dokdo.

4. The weather was so nice when I reached Dokdo.
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Are they all the same in meaning?
Which one should we use, #2 or #3? What is the difference between them? "I" was on a trip to Dokdo.

All are fine.

There is no real difference in meaning between 2 and 3.

All four mean the same thing, and all are correct. The difference between "at" and "in" is slight. "At" may mean you are in the Dokdo area, but not actually within the town limits. "In" means you are inside the city. Both can mean you are inside the city.

rfvv, does Dokdo have a town or village on it?

http://en.wikipedia.org/wiki/Liancourt_Rocks

If so, then Reed is correct.
If not, then #3 would not work.

Dokdo is made up of two main islands, Dongdo and Seodo, and 89 small islands. Dongdo and Seodo are very small. Only a few residents live there and there are more than 30 police officers who guard Dokdo.

Thank you. Good information. The photos on that webpage made me wonder if any people could live there. It seems so rocky, without much level space to build homes.

=)

In that case, "in" would be incorrect. I did not know what Dokdo is. Sorry. Writeacher is right.

Well, maybe not. While my knowledge of South Korean geography is woefully incomplete, I might say the weather was nice when I arrived in a U.S. state, such as Florida or Minnesota, or in a region such as "the south of France" or the Italian riviera. I would be "in" that region.