They like to feed close to morning and dusk. That allows them to not be seen as easily by their prey, so first thing in the morning and late afternoon are the best times to stay out of the surf if you dont like the chances of your foot looking like a delicious meal. Usually up to the first sandbar is safer than between 1st & 3rd sandbar. I know longer fish the surf because I am chicken.
I have plenty of stories about wade fishing and being investigated by swimming critters. some pretty close calls and some stolen fish too.
Scutter, that state record bull was caught close to mud over by super flats in the channel.
John
"Critics are men who watch a battle from a high place and then come down and shoot the survivors." Ernest Hemingway