A seal followed a group of canoeists on the River Severn for more than half an hour.
The 20 canoeists from a Wychavon club, who spotted it just outside Worcester on Saturday, described the encounter as "a bit strange".
Adam Hall, of the club, said: "[It was] swimming after the boats and nibbling our paddles."
An RSPCA spokesman said seals sometimes swim upriver following fish when there are peak high tides.
The seals are usually healthy and can stay around for as long as a couple of weeks before swimming back down to the sea, he added.
Mr Hall, of the Wychavon Kayak and Canoe Club, said the seal probably spent so much time with them because it was "a bit lonely".
The seal was also photographed in the area by Mike Finn catching and eating a salmon.
Mr Finn, 62, said he was cycling with his wife when he saw a group of people standing by the river.
He said: "I managed to squeeze between the trees and get a few pictures, when I dashed down to the river's edge it was gently bobbing along with the fish and struggling to consume it."