I was diving in Thailand this past May. I remember see'ing a lot of these ghost-pink jellyfish in the water, EVERYWHERE! Naturally I avoided them. On this dive we had very low vis and lost my AOW instructor, when I surfaced we had been separated quite a bit so the boat picked me up to drop me off again near him. He had mentioned that the jellyfish wouldn't hurt you. He found out the hard way of running into one face first. I didn't worry as much after that. I believe this was at Koh Dok Mai. We then went to the King Cruiser wreck. I didn't see nearly as many jellyfish there, however, I was stung somewhere in the middle of my dive but wasn't an extreme sting. Just a little irritation.
I'm not sure if what stung me was the same as all the jellyfish I had seen prior. Also, these same ghost-pink jellyfish were surrounding the boat on the way back to port. I checked my pictures for this trip and didn't see where I had snapped any of them. However, I have found a picture of what I was see'ing. They were literally everywhere, almost completely unavoidable. But keep in mind, I'm not sure if this is what stung me or not, but apparently I didn't have the type of reaction as posted now.
Being never stung by a jellyfish prior to this in my life, I wasn't sure what it was supposed to feel like anyway. I just always remembered my family members screaming if they got stung.... (we were children then).
But on a side note: I'm still looking forward to diving in Thailand again in August!