This almost perfectly circular turquoise lagoon is its own ecological island, like a square patch of forest floating on a surrounding sea of deforestation. To see it from the air is to get a crash course in tropical forest management and the significance of ecological islands.

The razor-sharp park boundaries stand out from the quiltlike fields all around this giant mirror in the middle of nowhere. You’ll probably arrive by land, but this description at least gives you some appreciation for the natural beauty of this park and the need to protect it from those who might further encroach upon its boundaries.

Already, logging operations have unscrupulously harvested some of the forest’s giant mahoganies with reckless disregard for what is, on paper at least, a national park. But I digress.

The 14,500-hectare Laguna Lachuá National Park (tel. 4084-1706, http://lachua.org/en, $6.50 admission) is still one of the most beautiful places on earth, despite its challenges. Here you can enjoy the refreshing waters and the dense forest all around in an atmosphere of utter tranquility. From the banks of the lagoon, you can see the forested peak of La Sultana

There are more than 300 species of birds found here, including mealy parrots and keel-billed toucans. Jaguars still roam the park and you can sometimes see footprints.

The lagoon’s Caribbean-like waters contain calcium deposits and high levels of sulphur, indicating the probable presence of petroleum beneath its waters.

The lake lies partially below sea level, at an altitude of 173 meters above sea level but also 222 meters deep. One of the more exciting theories concerning the lake’s formation contends the lakebed is an old meteor crater, with the rest of the meteor that created it having fallen near Cobán in an area known as the Nim Tak’a depression.

There’s a visitors center where you’ll find cooking facilities, a campground, a shelter with bunk beds ($4 p/p), showers, hiking trails, and canoes for rent ($1). You can string a hammock up for $0.75.

Getting to Laguna Lachuá National Park

The park’s main entrance is a few kilometers before Playa Grande as you come along the road from the east. From there it’s a four-kilometer walk to the lakeside through some very nice forest trails.