Las Guacamayas Biological Research Station (tel. 7926-1370, www.propeten.org ) is owned by ProPetén and welcomes visitors. The biological station sits amid verdant jungle on the shores of the Río San Pedro, a 20-minute boat ride from the village of Paso Caballos. It is one of the best places in Petén  to combine wildlife-viewing and rainforest trekking while staying in relative comfort, offering easy access to the ruins of Waka’-Perú  and the surrounding forests.
The current facility is the second incarnation of the biological station; the first was burned to the ground by angry villagers from Paso Caballos in the 1990s. ProPetén has since worked on strengthening ties to local communities and educating them about conservation.
You may contact ProPetén directly if you wish to stay here, as you don’t need to be on an organized trip (Scarlet Macaw Trail) to book a room. It’s recommended that you stay at least one night, as the station’s remote location doesn’t make for a reasonable day trip.
A stay here can be arranged with or without meals, and you are free to use the kitchen to cook your own. There are basic dorm rooms with stiff mattresses, shared bath, mosquito netting, and screened-in rooms accommodating up to 20 people. For extended stays, try packing a sleeping pad for extra cushioning.
Nice views of the river and a series of nature trails round out the list of amenities. The shortest trail leads to an observation tower, where you have a sweeping view of the Río San Pedro and the wetlands of Laguna del Tigre National Park  west to the foothills of the Sierra del Lacandón. There is a six-kilometer-long network of trails but it was awaiting repair because of a series of forest fires affecting areas near the station in 2003. Much of the forest traversed by the trail was burned to the ground.
In the evening, you can go out on the river in search of crocodiles with the station’s staff. Bird-watching is available in the mornings. There are observation platforms inside the site of Waka’-Perú where the scarlet macaw project operates. The staff may offer photo safaris whereby you can watch and photograph macaws from a platform sometime in the near future. The best time to visit for a glimpse at nesting macaws is during February and March, though the macaws can usually be seen between November and April.
A two-day, three-night package including meals, accommodation, round-trip transport from Flores, bird-watching, and a tour of El Perú costs $300 each for two people, but better deals can probably be found through one of the Flores guide companies .
Volunteers are also welcome at the biological station. During one of my last visits, two Spanish women were busy on a two-week tour of duty recollecting animal droppings for scientific investigation as to the health of local populations of certain species. Volunteers provide their own food and pay an average of $7 per day. The station prefers a two-week minimum commitment. Other activities you may be asked to assist with include wildlife monitoring and trail building/maintenance.