Over the years, scientists have dramatically changed their minds about Titan's surface. In the 1990s, the NASA/ESA Hubble Space Telescope spied an area on Titan that was brighter than the rest.
More recent observations show the same feature better. What are these bright and dark patches? Some scientists believe the bright area could be a continent and the rest oceans, but no one knows for sure, yet.
The recently discovered large continent-sized feature (red) is called Xanadu. It is unclear whether Xanadu is a mountain range, a giant basin, a smooth plain or a combination of all three. It may be dotted with hydrocarbon lakes but that is also unknown.
All that is presently known is that in Earth-based images, it is the brightest region on Titan. There is no doubt, though, that the surface appears very diverse, not uniform. There are a lot of surprises waiting for us there.
Where will Huygens land? ESA scientists predict the probe will land close to the bright patch, but not on it. This could be a landing in an ocean - which would be the first splashdown landing in an ocean off the Earth!
To land on an ocean would probably mean better data from Huygens. Even if the probe lasted only a few minutes before sinking, it would at least stay in an upright position. Being the right way up is essential for sending the data back to the Cassini orbiter and to the scientists on Earth.
Moreover, some of Huygens's instruments are better prepared to analyse liquids. If Huygens lands on a solid surface instead, there is a higher risk of falling in the wrong direction and not being able to easily communicate with Cassini.