Third attempt tp meet up with the hammerheads. First two were nice dives, but no sharks. Into the war at first light, then meet up with others at 10m then down slowly to 30m and waited. Visibility relatively low at around 10m. First saw a shadow, then a scalloped hammerhead passed at a three metres. After about 15 minutes, saw a further three hammerheads at the edge of visibility. Back to the reef at at 16m after 34 minutes with no more sightings.