A porbeagle! Not many people can say they have had a close encouter with one of those rare creatures! One of those experiences that is great, in hindsight.
We have to be very careful of large sharks when diving in the warm waters of our east coast, especially the bull sharks. Our dive group's policy is to exit the water when ever the sharks become threatening. (It is their domain after all.)
We had an encouter with some humpback whales in Mozambique recently. I was on my way down when they appeared out of nowhere. It was a great experience but to be surprised by the pod like that was rather un-nerving.
Two of our group were under them when they came through and their float line got caught in one of the whale's pectoral fins. Luckily a barnacle cut the line.
Humpback Whale encounter ExFL - YouTube