The local swim instructor who was training for a charity event said at first glance she initially thought it might have been a dog.
Surprised when she realised it was a seal, she said she was “a little bit nervous”.
“I just thought well if I just keep swimming and not bother it, it will probably go away but that wasn’t the case,” Mills said.
As a regular swimmer in the area, she said she always tries to keep away from any wildlife.
She added: “I didn’t really have much option here we were swimming together.”
Mills said at times she would stop to see if the animal had gone underneath her but then noticed it had stopped up ahead of her as if it was waiting for her.
She has since nicknamed it “Mr Seal” though she admitted she was not really sure if it was male of female.
“I felt very humbled to be able to swim with this seal,” she said.