The shark attacks there are not well publicized because of the effect it might have on tourism, but big Tiger Sharks are not uncommon.
Not sure if there are many attacks in that bay, but that was gutsy.
There was a great bar restaurant on the Kamehameha on the way up to the North Shore called The Crouching Lion. Have you ever gone in there? They have an incredible drink called a "Spider Lily" - but really strong - designated driver recommended.
I remember one weekend going up to the North Shore and we made friends talking with some local guys who were filming the tourists on the beach. We asked why & he said, "Just watch".
Sure enough a newlywed couple heads down to the surf and of course the girl is in a bikini. The first big wave hits her and off comes the bikini top. In goes the husband to save the day and help her cover up and get out of the water with her dignity, but they turn their back to the ocean. Bam, a big wave crashes down on them and they are both scrambling wobbly to the shore.
The guy says he played the films for fun at the locals bar (to which we were not invited).
He taught us the two rules of the North Shore - never wear a bikini into the water there, and never turn your back on the ocean.