From above
"It has been so prevalent that in some circles it is believed that where there are dolphins there is no danger of shark attack. Unfortunately this is not true. While dolphins are able and sometimes willing to protect humans from sharks, they may not."

While living aboard a boat in the Lahina Roadstead, Maui the was many nights that I ended up swimming home, btween 1/3 to 1/2 mile at night. There were 3 of us & only 2 dingys. When dolphins were known to be in & around the roadstead or harbor it was common for many of us to swim back & forth to shore. It was not near as common when dolphins hadn't been seen or reported to be swimming about. A lot of time the dolphins would wake me up by there sounds coming through the hull & when going topsides they'd be doing there tricks so close to the boat you could reach out & touch them. What a way to wake up in the morning.

Barry