Almost every diver that visits Heron Island ends up snorkelling or diving Heron Harbour. This man-made harbour allows boat access to the island, but also attracts a surprising amount of marine life that is clearly visible from the jetty. This spot is best dived or snorkelled at high tide, but even then the depth is only four metres deep.
Under the jetty are schools of sweetlips, trevally and numerous gropers that circle the pylons. The sandy bottom is a resting place for stingrays and shovelnose rays, but also common are lionfish, reef sharks, turtles and eagle rays. Unfortunately you can only get in the water in Heron Harbour in the early morning or late afternoon, as at other times access is restricted due to boat traffic.