An Old Quay at Mumbles 

Everything flows and nothing abides,

Everything gives way and nothing stays fixed

                                                                                                                         Heraclitus

  Here are some sources which are worth exploring:- 

There was  an ancient quay at Mumbles, which is referred to in the Cromwellian Survey of Gower of 1650 (p68) as 'The Key of Mumbles within the said Lordshipp' which hath, 'acustom payable by strangers. Vitz., for every stone of wooll there laden and unladen ob. [½d]; for every boatload cattle iiijd; for every tun of iron ijd; and alsoe Killage.' (keelage as at swansea).

The Lord hath a Quarry of limestones in the comon or Wast ground called Mumbles Clift which may be lett per annum xli

          The Tenants claims comon  for all manner of cattle sans number in these wast grounds following viz. Clyne Moor, Mumbles Clift, West Clift, Summer lift and Norton Burroughs and that the Inhabitants of Manselfield, Norton and Oystermouth Jute Xoon in the said Clyne Moor.

Cromwellian Survey of Gower, 1650, West Glam Archive D/D MG1

The encroachment of the sea in Swansea Bay is referred to by Captian Huddart in his report to the Harbour Trustees. 'within 150 to 200 years the contour of the bay has been considerably modified. We possess a plan of the Dunns at Oystermouth of 1663 upon which is plotted a considerable tract of land to seaward, . . . but which has now disappeared. The remains of a bed of peat with here and there stumps of trees, mark the encroachment in the neighbourhood of Blackpill  (see also p 93)The history of the Port of Swansea by WH Jones p355

 About the end of 18C Edward Llwyd's correspondent referring to Oystermouth, said, 'Within y't parish is a common port or passage into England, wherein is builded a Key for that purpose,' and as the parish extended to the river at Blackpill, it may well have been that the Quay shown on the old map is that referred to in Parochialia, supplement to Arch. Camb., 1911, p142

But is the Oystermouth mentioned, the Parish (which stretched from Blackpill to Mumbles Head and around to Caswell) or  the village?

There is a chart of Swansea Bay, 1795 which suggests that at a later date a quay was provided at a lower line of high-water than prevails today.The history of the port of Swansea by WH Jones,   p353, 1922,