英语听力：自然百科 伯利兹蓝洞

 Why is this diver burrowing 1 into the bottom of this mini lake? She is literally 2 disappearing into the sand and gravel 3 of the water’s floor, only debris 4 and the occasional bubbles from her breathing tank are visible. She is part of the project, largely funded by National Geographic 5, to dive into the sacred pools of the ancient Maya.

 
"Our exploration team discovered this upwelling, it’s an underwater spring upwelling, and it provides this magical experience because it’s located at the bottom of a very large crater 6, and you come down, down, down, down into this large crater, and in the bottom is this boiling mass of sediment 7 that’s actually being boiled, rolled and boiled, it’s almost like a natural lava 8 vent 9. Whet 10 in over the lip of the crater, descended 11 down into the bottom, and I didn’t want to have any interference with the water that was already in the pool, and so it required a little bit of digging, and frankly 12 it was extremely low visibility down there but below the actual base of sediment, there’s about one and a half meters more space. The water coming out of the bottom of this spring, coming into the pool, is chemically actually quite distinct from the water in the pool."
 
 
But this is just the beginning. The dives also revealed clues to past life here, and a first for the country of Belize. Scientists discovered several fossil beds around 60-90 feet below the surface, including femur bones the size of a bowling 13 ball. They also found tusks 14 and pelvic bones. These are the first recorded fossils ever found in Belize.
 
"And we left those in place. We only have removed a few small fossils so we can actually determine, are they fossilized? Or bone? They are definitely fossilized, so we know they have to be of a certain age. But were they here? Were these mega-fauna present during occupation by humans about 20,000 years ago, 15,000 years ago? Or are they much older?"
 
 
The dives were made in several pools in central Belize earlier this year in an area known as Cara Blanca. The researchers found evidence that the eight pools of the 25 they studied are likely connected through underground passages. Principal Investigator 15 Lisa Lucero says the major goal is to look for archaeological remains 16 underwater.
 
 
"Because the Maya considered openings in the earth caves, water bodies as portals to the underworld of Xibalba, and because the thousands of caves that have been found have offerings, ancient Maya offerings, we just knew that there'll be offerings at the bottom of the pool, so we came with the goal of trying to dive to look for these offerings."
 
 
Though they didn’t find offerings on the first dives, they did find ceramic 17 sherds in a pool near remains of Maya buildings, constructed around 1100 to 1300 years ago. Lucero says there is no indication this area had many residences, but rather was likely a pilgrimage site, with Maya traveling here from hundreds of miles away. Because at least one of the pools was found to be around 200 feet deep, and littered with trees and silt 18, more sophisticated diving equipment is needed for future dives, and Lucero believes there are more significant Maya offerings at these depths.