The Sacred Cenote is a water-filled sinkhole in limestone at the pre-Columbian Maya archaeological site of Chichen Itza, in the northern Yucatán Peninsula. It is located to the north of Chichen Itza's civic precinct, to which it is connected by a 300-metre sacbe, a raised pathway. According to both Maya and Spanish post-Conquest sources, pre-Columbian Maya deposited valuables and human bodies into the cenote as a form of sacrifice to the rain god Chaac. Edward Herbert Thompson dredged the Cenote Sagrado from 1904 to 1910, and recovered artifacts of gold, jade, pottery, and incense, as well as human remains. Beginning in the 1950s several Mexican-driven projects were conducted in the cenote, including a 1961 project that used an airlift dredge. The northwestern Yucatán Peninsula is a limestone plain, with no rivers or streams, lakes or ponds. The region is pockmarked with natural sinkholes, called cenotes, which expose the water table to the surface. One of the most impressive of these is the Sacred Cenote, which is 60 metres in diameter and surrounded by sheer cliffs that drop to the water table some 27 metres below. According to sources, the Sacred Cenote was a place of pilgrimage for ancient Maya people who would conduct sacrifices into it. As Friar Diego de Landa observed in 1566 after visiting Chichen Itza: "Into this well they have had, and then had, the custom of throwing men alive as a sacrifice to the gods, in times of drought, and they believed that they did not die though they never saw them again. They also threw into it a great many other things, like precious stones and things which they prized. And so, if this country had possessed gold, it would be this well that would have the great part of it." Archaeological investigations have removed thousands of objects from the bottom of the cenote, including artifacts made from gold, jadeite, copal, pottery, flint, obsidian, shell, wood, rubber, and cloth, as well as human skeletons. Many perishable objects were preserved by the cenote. Wooden objects which normally would have rotted were preserved in the water. A great variety of wooden objects have been found including weapons, scepters, idols, tools, and jewelry. Jade was the largest category of objects found, followed by textiles. The presence of jade, gold and copper in the cenote offers proof of the importance of Chichén Itzá as a cultural city center. None of these raw materials are native to the Yucatán, which indicates that they were valuable objects brought to Chichén Itzá from other places in Central America and then sacrificed as an act of worship. Pottery, stone, bone and shells were also found in the cenote. Archaeologists have found that many objects show evidence of being intentionally damaged before being thrown into the cenote, and have speculated that this intentional damage is meant to be analogous to “killing” the object as a sacrifice.