How do you get to the shivering isles in oblivion

a marker on your map appears, its southeast of the imperial city. it should be on a small island, and you should be able to find you way from there its not right there, but its down the river, SW of the imperial city. ------------ it's in the middle of niben bay and it will only be there if you have the expansion pack. also, once you've installed it, a pop-up should appear after a while of playing, putting a marker on your map, showing you where it is ------------ These 2 are correct, but you have to have the shivering isles expansion pack.