The Great Marsh is the Safari-Zone style area in Pokemon Brilliant Diamond and Shining Pearl. This location is where you can go to find rare wild Pokemon (along with a few other items). You will be able to access the Great Marsh after reaching Pastoria City. It is located in the northern section of the city and will cost you 500 dollars to enter.
Before entering the Great Marsh, use the stairs to go up to the second floor of the building and use the telescopes. Each use of one will cost you 100
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