Over several flybys past the moon covering a period of two-and-a-half years, the spacecraft mapped a large area of the surface of Titan, sometimes covering the surface twice.
What it found on its return passes was that easily recognisable geological features on the surface of the moon were not in their expected coordinates with some out of position by as much as 20 miles (30 kms).
Using data collected by Cassini, combined with models of how the moon spins, scientists have concluded the odd rate of spin could only happen if a large underground ocean lay beneath Titan's crust.
In an article in this week's Science journal, reseachers, led by Dr Ralph Lorenz of Johns Hopkins University Applied Physics Laboratory, US, have suggested their predictions be tested by extending the Cassini mission or sending future missions to Titan.
Speaking to the BBC, John Zarnecki, Professor of Space Science, at the UK's Open University - who was not involved in the study - said the motivation to return to Titan was "overwhelming".
"We know there are organic molecules, the place is swarming in organics," he said.
"Titan is 50% water-ice. If it is liquid, as this paper is implying some of it is, it looks as though we've got at least two of the things to initiate the chemistry that leads to life."
"It wouldn't be too far fetched to imagine certain spots on Titan where there would be a source of energy - maybe geothermal energy, as we have on Earth at the bottom of the oceans," Prof. Zarnecki added.