The 12ft basking shark was photographed by paddle-boarders in Torquay Marina on Wednesday.
Members of Torquay Water Sports described it as an “amazing sight”.
“A basking shark popped in for a look around and then slipped back out again… almost unnoticed,” they said.
“An amazing sight indeed.”
The basking shark was spotted in Torquay Marina (Torquay Water Sports/PA)
The shark was also spotted by members of the RNLI, who estimated it to be between 10ft and 12ft in length.
A RNLI Torbay spokesman said: “The largest fish in British waters, basking sharks are typically anything up to 28ft and can weigh 9,000lb.