While it is impossible to know for certain when a shark may be nearby, there are some warning signs that can alert you to their presence. First, look out for any splashing or thrashing in the water. Sharks don't swim like other fish, so this may indicate that something larger than your typical fish is present. Additionally, listen for snorting and growling sounds coming from beneath the surface of the water. If this kind of activity continues, it may indicate that a shark is around. Another way to detect sharks is by watching out for birds hovering over areas where they feed on smaller fish which have been stirred up by predators such as sharks below them.