It is not known whether the mudflat that was to become Sunk Island was established by the early-mid 14th century when Ravenser was functioning as a port (s.p.b.s). Certainly two centuries later when Lord Burleigh commissioned the first navigational map of the Humber Estuary (c. 1560) the mudflat on which, at its western end, the colonisation of Sunk Island was to begin was shown (see above), a channel sufficient for a sailing ship to pass along (see above the ship drawn between Patrington and the mudflat) still separating this mudflat from the south Holderness coast proper. Burleigh’s map/chart is hard to study without access to a large scale copy. Just over a century later a Humber navigational chart compiled by Captain Greenville Collins, hydrologer to Charles II, showed Sunk Island, still clearly an island with water channels to both north and south but with the name written on, shown as vegetated and outlined by what must have been a clay-bank (flood defence). The un-colonised part of the mudflat to the east is named as Sunk Island Dry/Bay (not clear).
Today the once shipping channel to the north of Sunk Island is only defined by a substantial drainage channel and the whole area up to the villages of Keyingham, Ottringham and Patrington (once on the coast) is now one of reclaimed land, the estuarine silts forming one of the most fertile areas for arable farming in the country. The north bank of the upper Humber Estuary (south Holderness) is thus the southern edge of Sunk Island.
Two valuable sources of information on this challenging but fascinating area are;
Meadley, J. A Sunk Island Miscellany (Malet Lambert Local History Original, Vol. 40, with a Forward by the late Geoff Bell).
Poulson, G. The History and Antiquities of the Seigntory of Holderness (2 vols., 1840).
Also Boyle Lost Towns of the Humber (early 20th century).
All three will be most readily accessed in Hull History Centre.