days a year. The park is divided into four sections by direction: the northwest includes medium-height, somewhat deciduous rainforest as well as some lowland rainforest and grassland, found in the municipalities of Osumacinta and San Fernando; the western section has similar vegetation, and is located entirely in San Fernando; the eastern section has forests of pine as well as medium-height semi-deciduous rainforest and grasslands, and is found in Chiapa de Corzo; and the southeast has most of the sides of the canyon itself and a navigable section of the Grijalva River, but only remnants of medium-height rainforest and pachycaulous vegetation. The main land access into the park is from Tuxtla Gutiérrez north through Osumacinta then past the Chicoasén Dam. Another access point is from Chiapa de Corzo by boat from the Cahuaré Docks. As the main attraction of the park is the canyon, several lookout points have been constructed on various parts of the rim. La Ceiba is closest to the city of Tuxtla Gutiérrez, only away. The Los Chiapas point is near where the canyon's walls rise highest from the river below, where according to legend, a number of Chiapa people preferred to commit suicide by jumping rather than submit to Spanish domination. This lookout also has a restaurant. Conservation issues The most important conservation issue in the park is the contamination of the Grijalva River, which passes through the Sumidero Canyon proper. However, other threats to the park include human encroachment and other human activities. An estimated 1500 to 2000 hectares, or about six percent of the park total, have been encroached upon, mostly by illegal human settlements next to the city of Tuxtla Gutiérrez since the park was established. It is estimated that about 15,000 people live within the park's borders. Most of these illegal constructions belong to the very poor who have migrated to the city from elsewhere. The demand for living space has created an industry of illegal subdivisions which are then sold without the proper title to victims. Three of the main neighborhoods to develop in this way are the Patria Nueva Alta, Arroyo Blanco, La Esperanza and Las Granjas. The encroachment is a result of the fast population growth of Tuxtla Gutiérrez and Chiapa de Corzo. The growth of these areas has led to land ownership disputes, loss of wild habitat and deforestation. In 2002, the federal and state government signed an accord