Oh no, please don't!!! I've done that, and it is no fun at all!
Strange you should mention stingrays. We went swimming with the Manta rays off the Kona Airport last night. Here's a link to the event on one of the Hawaii touring sights, as well as a picture of what brushed my belly during the feeding. Manta rays are very gentle, and have no barb. This was simply the most awesome other-worldly thing I have ever done, and highly recommend it to anyone who isn't afraid of the water.
