 A shark was spotted swimming 30 yards from a break wall along Oahu's south shore. Beachgoers are being advised to check in with lifeguards before entering the water. This even though Honolulu Emergency Services has labeled the shark non-aggressive. They say there have been no reports of injuries or attacks. That being said, tiger sharks are known for being extremely aggressive and have often been known to attack humans. Gary Baumgarten, Fox News.