'Wiped out': Mexico railway raises fears for cenotes
STORY: Beneath the ground in Mexico's remote southern jungles are ancient cave systems known as cenotes.
They form part of one of the most unique ecosystems in the world.
But at the Dama Blanca Cenote, environmental activists say that ecosystem has been "wiped out".
From the entrance to the cave you can see the alleged culprit.
This ancient area has, in recent years, been home to the Tren Maya railway project.
"Unfortunately, we saw how they razed the jungle that covered it. They left it unprotected".
Environmentalist Jose Uribe says the entrance to Dama Blanca was filled in as part of the train line construction.
It was once, he said, an area rich in bats, vegetation and fish.
"The functioning of the ecosystem of the cenote has been eliminated. As it's a jungle, the function it provided has been wiped out. Dama Blanca is dead."
Cenotes are formed when the surface limestone collapses to expose the crystalline groundwater.
They have been the sites of discoveries such as ancient human fossils and Maya artifacts.
Last year President Andres Manuel Lopez Obrador said that, where there are underground rivers or cenotes there would be detours or bridges.
The government argues Tren Maya will bring modern connectivity to areas that have, for generations, been deprived of significant economic benefits.
It will connect Mexico's top tourist destination Cancun with ancient Mayan temples.
But the railway has deeply divided Mexicans: exemplifying the struggle that developing countries face when trying to balance economic progress with environmental responsibility.