I want to see tropical rainforest!

Chiapas, Mexico... Palenque area is very tourist friendly and you should have fun there (most people do). I was speaking with a tree expert there and he said it is only a first tier canopy and that you can find 3rd tier canopies in more dense areas like further down Central America and the Amazonian. Most of the jungle around the Maya sites is relatively new (1000 years old). Guatemala has some excellent jungle hiking up to El Mirador, going on a hike like this will give you jungle fever... I have it!

Ruins are often good places to find bright tropical birds on your own, in Yucatan you could try Uxmal and Calakmul is great (but tricky without tranport).

Calakmul (like other parts of Yucatan) is jungle but in much of the year maybe a bit dryer than many people expect - in May for example. The Chiapas jungle is more humid (so the danger of rain obviously bigger even in dry season - May is also regarded the end of the dry season here)

In Palenque or San Cristobal you should find agents offering jungle tours.
For example:
SENDASUR
Real de Guadalupe # 23, Centro
San Cristóbal de las Casas

One more comment...for those expecting endless jungles...the tropical jungles of Mexico (and elsewhere) are often now fragmented by agriculture and tours invariably also have to cross some of these less pristine areas.

My time is not that limited that maybe many of you think.

I will be arriving in Chetumal, anyway. Then I'm going to rent a car. Hence, driving to Calakmul is not that difficult. It only takes a few hours of my nine days on Yucatan. I would stay two nights at Calakmul going to some guided wildlife trip on day #2 and driving to the ruins on day#3 and then back to Chetumal to sleep. This would take three days only. Then I would head north (day #4) to see some cenotes (day #5) and Chichen Itza (day #6) and relax/swim (day#7). Flight home is day #8. As you can see, I cannot go to Sian Ka'an, if I want some "free" time on the Caribbean beaches. If I, on the other hand, skip Calakmul, then I can go to Sian Ka'an very well. Decisions, decisions...

So, given the time schedule above, what do you people think? Is Calakmul worth it? I realize that I will not see Tarzan and such :D as the "real" jungles are further south. But maybe a two canopy forest and some animals and exotic birds? I read somewhere about someone going to Yucatan and climbing a tower to the canopy, and above it, and then to the second canopy... So somewhere there must lie a small isolated patch of rainforest... If I search for "tropical rainforest" in wikipedia, I find a page with the Calakmul biosphere reserve mentioned. Next time I'll plan for the Lacandón/Peten or further south (and plenty of time), but a little taste would be nice now. And if anybody has been to Calakmul, how was it? Was it interesting? Educational? Fun? A disappointment? Spcifically, is it a two canopy forest and is there any possibility of getting up there to actually see that? I know that the ruins rise above the forest...

You can stop and see the rain forest near Catemaco, Veracruz . . . also.

Rast, I think Calakmul is worth it for the ruins. When we were there it was very quiet, we didn't see any other tourists. It is a spectacular site and you can climb Structure II in the Grand Plaza where you get an amazing 360 degree view of jungle with a few ruins poking through the top. We felt like we were the only people in the world, it was so peaceful.

In terms of wildlife however I was slightly disappointed at Calakmul - I thought we would see some toucans, maybe some parrots and/or monkeys but none were to be found. There were signs around saying that howler monkeys live in the forest there but I guess they were hiding that day. We may just have been unlucky, other people may have a different experience.

The ruins at Kohunlich are quite "jungle-y", a bit more rainforest looking than other places we saw (i.e more "palm" type trees - I am not an expert in the environment!!!!). We saw some fun colourful birds and snakes! The ruins aren't too far from Chetumal so maybe if you have time they could be worth a look - again, they are very quiet with very few visitors.