Dolphins are awesome, had them bow riding on yacht and 5 smimming alongside and underneath my windsurf longboard. Its the orcas that I'm not do keen to get close to.
About a year ago we had a couple of sessions where the dolphins would come up under the foil and nudge it resulting in a big crash. I like to think they were scratching their backs on the foil.
They were gently bumping me while I restarted in the water. It was awesome, but a bit scary. There are beasts bigger than me jostling me in the water.
The same thing happened the day before to an Italian kite foiler. He thought they were going to eat him.