A point in the passage where two cave divers cannot pass through side by side is called a restriction.
Calcite rafts (calcium carbonate crystals) may form on the surface of still water. Cave diving in Mexico we sometimes see them on the water at cenotes or in air domes inside the cave.
Cenote Chan Hol in Mexico offers the cave diver shallow, highly decorated passages. Translated from Mayan as "small hole", the cenote was discovered in 2003.
Chamber of the Ancients
Located in the downstream section of cave from Cenote Car Wash in Mexico is a room called the Chamber of the Ancients. It is proposed that the prominent triangular rock in the foreground, that contains charcoal, was used for cooking 11,000 years ago.