The Roman Map of Britain Locus Danoui on the River Don, Yorkshire

Daunoni vars. Danoin, Dannoni also read Dannom (R&C 235) next

As with Locus Danouius (R&C 230) this is based on Danuvius. By its placement after Segeloci we can be fairly certain that this name refers to a water feature on the Yorkshire Don. The pale green in the map below represents the flood-prone areas of the Humber tributaries, both riverine and tidal. This would correspond to the portion of the Humberhead Levels south of the Vale of York. 

    I believe the first to recognize Daunoni (and Segloes) as related to Dano (and Segeloci) was Arthur William Whatmore in his 'Insulae Britannicae, The British Isles. Their Geography, History, and Antiquities down to the Close of the Roman Period' (1913).