If you are talking about top 5 dives of your life - this has to be one of them!
This was day one while diving from the Blue Voyager dive safari boat (from Blue O Two) - we descended down to expect half a dozen Grey Reef Sharks only to be confronted by 30 of them, all circling in the current!
Completely unexpected and even caught the dive guides by surprise, as they had never seen these numbers before!

A number of sharks were heavily pregnant as can be seen in the video, with many of the females having fresh bite marks on their rear quarters indicating that there could have been a recent occurrence of fornication.

The sharks were all circling when we arrived, and still there in numbers when we left 60 mins later - we revisited the same location the following morning only to find that every single one of them had disappeared.

A truly once in a lifetime experience, that we were literally in the right place at the right time for!
For the rest of the week while diving we referred to this as 'our very own Blue Planet 3 moment'