David Lamb
Google
It's a hole. It's neat to look at the geography of the island (limestone) and it suggests much cooler cave systems to be had...but this is just a hole. It's worth about 5 minutes of your time, so if you're on the Long Bay Beach side of the island, swing by. Otherwise, I'd just as soon ignore it. There is a rope...but don't be tempted to go down the hole if you want to ensure you can get out. The sunset from nearby was quite nice, though.