In the early nineteenth century the Port of London extended from London Bridge to Deptford. It comprised the Upper Pool, stretching from the Bridge down to Union Hole; the Middle Pool, the part from Union Hole down to Wapping New Stairs; and the Lower Pool, from there down to Horseferry-tier, near Limehouse. These three stretches, the medieval port, were for ships of from 250 to 400 tons. Below them were two further stretches, also part of the Port of London, but more lately come into use; the first from Horseferry to the mooring chains at Deptford, the second being opposite Deptford itself. Of these, the one was fit for ships of 450–500 tons, drawing seventeen or eighteen feet of water, the other was deep enough for the biggest ships in the Merchant Navy. Including colliers, of which there were about three hundred, and coasting vessels, some of which might lie between London Bridge and Blackfriars, the whole Port could contain as many as fourteen hundred vessels at once.

The only part of the Port of London used by the East India Company's ships was the lowest stretch of all, that opposite Deptford. A great many Indiamen had their moorings there. Those that did not moor there, moored at either Blackwall or Northfleet. These three anchorages were opposite the yards where the ships were built and repaired. A ship's arrival at Deptford, Blackwall or Northfleet, after fitting or refitting in dock, in the Brunswick basin or elsewhere, was known as ‘coming afloat’, and it was the first stage in the process of commencing a voyage.