Amsterdam's waterfront, which used to be a lake or bay. And yes, it is IJ not Ij because IJ is sort of the Dutch Y, thus both letters are capitalised. With the creation of new polders, the IJ has become squashed and reduced in size.

One of the best places to appreciate the IJ is to watch the sun go down from the terrace of the new concert hall Muziekgebouw aan 't IJ