Grants Gap is located near the northern end of the Heron Island reef on the eastern side. It was one of the closer dives to the harbour, being a bit past Pams Point.

The reef wall here runs north-west to south-east and sort of looks like a cow's under when viewed from above with each of the teats being a canyon that extends into the coral reef. There was a mooring (I think) on the sand off the most spectacular of the canyons.

A very rough map I drew of Grants Gap in 1989 Note depths are in feet

Once on the bottom the depth is about nine metres or less. The bottom is composed of sand with some coral outcrops. Head over to the reef wall (about six metres deep) and you should see the first of the canyons. Go a bit past to the north-west till you have gone about 30 metres. If you see no more canyons, the first one you saw is the one to start at. Go back and enter the canyon. You will see that it runs back into the reef for perhaps 10 metres. There are often crayfish and moray eels in these canyons.

Exit the canyon and follow the wall to the right. This will take you to the next one which is not that far away (less than 10 metres). This canyon is a bit wider and longer and again should be explored. Once out, turn right again.

The next canyon is the most interesting one. Ahead it gets dark and once you get closer, you will see that there is an archway or tunnel. This leads to a sinkhole like formation. Ascend up and you will be on top of the reef in a few metres of water. Swim back towards the canyon and drop back down to the sandy bottom.

When you are out of the canyon, turn right once more and follow the reef wall. There is another canyon about 20 metres along that should be explored as per the previous ones. About 30 metres past here there is a small bay and 25 metres on another. Between the two bays you should see a larger coral bommie a bit off the wall. After you have explored this last bay, head back to the bommie.

After examining the bommie, head back to the mooring area and if you have time, you can again look at the archway/tunnel.

On this dive you should see turtles, white-tipped reef sharks, unicornfish, parrotfish, batfish, bannerfish, flutemouth and more. A nice dive site.

Note this article was written in 2008 so my memory may be a bit out with some aspects of the dive site and things may have changed in the almost 20 years since I last dived there.