A seal swam into St Saviour's Dock in Bermondsey on Sunday morning, causing a stir amongst local residents.
"She was on one of the bird nesting platforms for about 30 minutes before pushing off as the tide started going out," says Robert Wilkinson who took the fantastic photo above.
"She looked alert and healthy as far as I can tell."
The seal's presence was also reported on the SE1 forum.
The Zoological Society of London carries out a Thames Marine Mammal Survey and asks anyone who spots dolphins, porpoises and seals in the tidal Thames to report the sighting.