The Stingray in my picture has a 4' body length, 6 foot width, with an 18" stinger; she weighed at least 150#, and had you stepped on her, the most likely outcome would be a drowning, as you could not pull the barbed stinger out of your leg while she fled to deeper water.
I have a 2" scar from a little stingray that hit bone on my ankle, and have "kicked up" 3-4' stingrays while gigging flounder. I have also castnetted mantas in the 12-14' range (their wing swirls on the surface look just like 2# mullet swirls, 8-10' apart), that had I not used the proper method would also have drowned me.
I have had my boat rubbed by whale sharks, had 500 pound tiger sharks leap completely over the cockpit, and been followed by 15' hammerheads while swimming. I have had Marlin run out 1500 yards of line before I could grab the rod and sit in the fighting chair and had unknown fish break 130 class boat rods (3/4" solid fiberglass).
I still like to flyfish for bass and bream in freshwater, though.
