From a story tonight on BBC Science and Nature
About Chicxlub crater on Yucatan Peninsula

http://news.bbc.co.uk/2/hi/science/nature/2837407.stm

The collapse of numerous limestone
caverns above the crater rim has
resulted in an arcing chain of
sinkholes - also visible in the shuttle
radar image.

"They are the result of extensive
erosion in the limestone. These
beautiful cenotes, as they are called,
are several metres across and were
in fact used by the Mayans to make their sacrifices.

cenote suh no' tay
n.
5AmSp < Maya tzonot6 a deep natural well carved out of friable limestone

used by the Mayans to make their sacrifices.

Interesting turn of phrase. We all make our sacrifices, but somehow I think the Mayans sacrifices were not about self-denial!

Dear dxb: The Sunday newspaper supplements used to feature gory
details of Axtecs cutting the hearts out of virgins before casting the
still quivering corpse into a deep waterfilled natural well. That kind
of sacrifice.

Weren't the human sacrifices in those parts usually enemies captured in battle? Somehow I doubt many of them were virgins.

Bingley

Dear Bingley: The Sunday supplements suffered no compulsion to stick to facts.

According to the tour guide I overheard at Chichen Itza, it was an honor bestowed on certain families to have their babies chosen for sacrifice. The babies were brought up in the knowledge that they would be sacrificed for the greater good of the tribe and their sacrificial ceremony when they reached the proper age (12?)was much like a wedding celebration. I have not been able to verify this.
http://www.jaguar-sun.com/maya.html
There were many forms of human sacrifice and some were captured enemy warriors. The truth is that no one really knows. I also heard the tour guide tell the tourists that the team that lost the match in the Mayan ballgame would be sacrificed. I can imagine that perhaps this happened at the end of a cycle, but not on a regular basis.
http://www.jaguar-sun.com/ballgame.html
There were about 159 hits on google when I searched "Mayan sacrifices cenotes". I will look into this further, later on.

Edit: Tour guides at the Mayan ruins suffer no compunctions about offering lurid details as facts, either. The tourists want to be titilated by "heathen worship practices", the gorier the better. The tour guides have found that the tips are better if they tell great yarns. Human nature, after all.