Police are asking people not to get too close to a humpback whale spotted off the south Devon coast.
It is believed to be with a calf and was last seen in Start Bay near Slapton.
Crowds have been drawn to the area, but a police spokesman said: "Please do not go anywhere near it on a boat".
The area is being patrolled by a fisheries vessel. Anyone caught harassing the whale could be prosecuted.
The Sea Watch Foundation, which records sightings of whales, said it was rare for humpbacks to be seen off the UK coastline until about five years ago, when sightings increased from about five per year to between 15 and 30.
Sea Watch director Dr Peter Evans said numbers rose to about 40 in the past 12 months, a record high.
He added: "They seem to be recovering and it could be just that there is a lot of fish about.
"They won't hang around anywhere unless there's food."
Lindy Hingley, from Brixham Seawatch, said: "I'm appealing to everybody to give it plenty of space and, if they want to watch, watch from the shore.
"Please don't go out in boats to try to get close to it."
Freelance film-maker John Walker said the 40ft long whale, first seen on Friday, had moved further out to sea.
"It was only about 15 metres off shore yesterday [Friday], so we were worried it might beach, but it has now gone much further out to sea," he said.