Lurking behind Warragamba Dam the long-finned eel waits for her chance to take the second great journey of a lifetime.
The life cycle of the long-finned eel is one of the greatest migration stories around. The adult eels swim 4000km to the Coral Sea, near Vanuatu, to breed. It's a journey of endurance matched only by the return trip of the tiny eel hatchlings.
The hatchlings, called Leptocephali, float on ocean currents for about a year, eventually arriving at the east coast of Australia. Driven by instinct they swim into rivers and head upstream.
By the time they reach Warragamba Dam the baby eels, now known as elvers, measure a mere 12cm in length. So how do they scale the giant wall?
The clever elvers actually detour around the dam wall. But it's no easy task: First they wriggle 300 metres up a rocky stream bed, then they climb a steep 90 metre embankment to enter a drain, they squirm 100 metres in a ditch beside an old rail track, then they duck under the road through a purpose built culvert, before wriggling a final 50 metres downhill into the lake.