The Sea Cicadas are not always found and I believe them to be a seasonal dish but I am not sure.
The deep fried sea cicadas are usually found on the West coast of Phuket - these were found adjacent to Maikhao beach. Here is some more information about the sea cicadas on that beach.
So what did they taste like apart from a little crunchy?
That would probably be the best description...
Try some if you are visiting Phuket.