Suping out behind the back breakers at a local beachy last year, I had a whale and her calf swimming about 100m from myself and a longboarder. As we were mid conversation - the mother broke away from her calf and swam straight toward us. I turned to paddle away when she got a bit close and just as she got about a metre away (I was a bit worried at this stage), she turned, kicked her tail and swam away.
The wake from the tail nearly knocked me off my board - awesome experience!