One of the divers shines a flash light in the depths of the sinkhole.
The 121 metre pit in the state of Quintana Roo, Mexico, is believed to be an ancient sacrificial Mayan site filled with animal and human bones.
The spectacular pictures were taken by American underwater photographer and scuba instructor Troy Iloski, who travelled with local tour guides Antonio Molina Piquard, Anna Nicolaus and Bernardo Miranda.
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