I have just read some reviews about tour operators and the prices, if you decide to go here DO NOT book through an operator, you are being ripped off. We took a trike and it was a nice long drive out, the entrance fee was only 600peso for the boat so we let the driver come along too :)
The fireflies are only small, and getting photos is virtually impossible because its so dark, personally I would say, don't worry about the pics just enjoy and remember it all, as a photographer I know how difficult this is to do lol
There is also something with the water, make sure you drag your fingers in the water to see it light up as if my magic, its beautiful to see!
The guide was great, he tells you all about the fireflies and by shining a red laser gets them to flash in harmony (used to deter predators because they look bigger), then he also uses a laser-pen to show you stars and constellations in the amazingly clear and very dark skies - it was awesome seeing the Milky Way and the stars so clear, here in England we only have 3 places that are so dark :/
I have rated it as excellent because we thoroughly enjoyed it, even though its a short tour, we learned a lot and my girlfriend got to see something she had wanted to see for years, so it made it all worthwhile and special :) and for 600 peso, it was a bargain :)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.