A warning has been issued to stay away from seals at Tentsmuir Point following reports of the animals being disturbed.
People with dogs off lead were spotted close to the mammals as they basked on a sandbar some distance out.
Frightened seals stampeding into the water can fatally injure their pups and become aggressive.
The tide can also come in quickly and cut off those who walk too far out.
Reserve manager Tom Cunningham said this was a critical time for seals as they haul out to rest, moult and breed.
He said: “When they get spooked they rush back in and their bodies are not ready for it.
“These people were walking miles out and the tide could easily have come in behind them.”
The incident occurred on Monday as sunshine and high temperatures brought visitors to the beach and forest between Tayport and Leuchars.
Litter and fires have also been problems as people make the most of the good weather.
After the disturbance, Tentsmuir National Nature Reserve issued advice warning people to stay at least 150 metres from the seals and keep dogs on leads.
It said: “Although the sunny weather and low tides may make you want to walk out on the sandbars to get close to the seals, please remember that these are wild animals.
“Do not walk out on the sandbars to get close to them, especially with dogs off the lead.
“Disturbance of seals may lead to them stampeding into the water from their haul out which can cause injury or death to young seals and aggression from the seals to you and/or your dog.”
Those visiting the reserve while coronavirus restrictions remain in force were also advised to leave if it looks busy and be aware some paths at Tentsmuir Point are too narrow to maintain social distancing.
The Forestry and Land Scotland car park at Kinshaldy and the Morton Lochs wildlife hides remain closed.
