To add to the exploration part of it http://www.gamesas.com/bgsforums/index.php?showtopic=1045160 adds alot of unique locations to the somewhat samely Cyrodiil landscape. If you use other mods you might want to see if any mods conflicts with UL and get a patch

Here's one of Oblivion's newest, most extensive, exciting, ambitious exploration mods: onra's http://www.gamesas.com/bgsforums/index.php?showtopic=1073491 This, combined with another new mod, Side777's http://www.gamesas.com/bgsforums/index.php?showtopic=1072969 opens up a whole new era in exploration.

Also worth checking out: Hazard's http://www.tesnexus.com/downloads/file.php?id=20461 Real-time cart travel.

This. I'm a bit puzzled about why the new heightmaps are not creating more of a buzz, especially when coupled with Side777's Sailing Mod
I've spent several happy days just wondering around Blackmarsh on foot, and exploring the waterways in Gurong, the small sailing boat. Also sailing along the Elseweyr/Valenwood coast between Leyawiin and Anvil