Wild Chestnut Horse
From the OblivioWiki – your guide to everything Oblivion
There is a wild Chestnut horse around Fort Alessia, but if you chase this horse towards the beach, the mud crabs will kill it, as there is lot of them down on that beach. You may try to catch it and ride it, however this is a pointless venture as, being wild as they are, they are unrideable.
