In every game of Morrowind I've played I've always made an enchanted jumping artifact of some sort (an aside: Jump being removed from Oblivion bummed me out like you wouldn't believe). I remember with one I was using a mod that altered the enchantment limits of items and the resulting just slightly overpowered amulet let me jump from the top of the Foreign Quarter of Vivec clear over the entire island and landed me somewhere in the Sea of Ghosts far north of Sheogorad. So yes, with a powerful enough Jump spell coupled with other related effects (Fortify Acrobatics for one) it's possible to jump anywhere you can imagine.