While reading about the ghost ship Jiang Seng I noticed that Wikipedia claimed it was drifting in uncharted waters in the Gulf of Carpentaria. I tried to find a primary source referencing uncharted waters but couldn't find any so this may just be one editor's penchant for artistic license.
Regardless it got me thinking: are there any oceans or perhaps other parts of the world that can still be called uncharted? Or has satellite navigation and imaging given us a complete picture of our globe?
There are many "uncharted waters". Nautical charts have information about water depths, dangers to navigation, aids to navigation, anchorages, and other features. You can see here what might be included in a nautical chart: U.S. Chart No. 1
The area in question is a shallow sea... so boats of different sizes may or may not be able to take certain routes depending on tides etc. Thus a nautical chart is important in these types of regions.
Yes satellites have mapped the world... and coastline is well defined. You can even learn about underwater depths using satellite instrumentation that detects gravity (e.g. CryoSat2) as discussed here: Global seafloor map reveals uncharted sea mountains, stunning details of Earth's oceans which discusses recent measurements of the seafloor from space.
University of Sydney geophysicist Dietmar Müller said about 71% of the Earth's surface is covered by water and roughly 90% of the seafloor is uncharted by survey ships that employ acoustic beams to map the depths. ... Müller said the conclusions the [satellite] researchers made about seabed topography may be less accurate than acoustic beam methods employed by ships.
and the article Gravity’s Magic: New Seafloor Map Shows Earth’s Uncharted Depths says:
The effect of the slight increase in gravity caused by the mass of rock in an undersea mountain is to attract a mound of water several meters high over the seamount. Deep ocean trenches have the reverse effect,” ESA wrote in a statement. “These features can only be detected by using radar altimetry from space.
Considering that the Mid-Atlantic ridge was just discovered recently (in geological terms), much of the Earth's water is still unmapped. The surface can be easily mapped by satellites, as said by farrenthorpe. It's just undersea territory which remains a deep mystery (no pun intended).
Some question the fact that we can estimate the depth of the Mariana Trench, but not map the seafloor. In that case, think about using a ruler. You can measure the length, width, or height of any object. But can you determine what the object looked like?
With advancing technology, more of the seafloor is explored everyday and sometimes we find new patterns, like the Mid-Atlantic ridge. Good luck geology!
A lot depends on the definition of "charted". How much detail must we know for an area to gain this status? As others have said, we have a low-resolution idea of all of the non-ice-covered seabed from satellite altimetry and gravity measurements - but there is a big difference between this, with a resolution measured in miles, and a high-resolution multibeam sonar survey in coastal waters that might resolve down to less than a metre.
Most of the planet is known to a very coarse level.
Much, but not all, of the planet's coastal waters have been surveyed at one time or another, often by colonial navies. A lot of modern Admiralty charts have sections for which the last survey was conducted in (say) 1882. These surveys were conducted by a man dropping a lead weight over the side of a ship and measuring how far it fell; neither their accuracy nor their resolution is up to modern standards and, even if the measurements were accurate when taken, sediments may have moved in the time since.
Very small areas of the seafloor (relative to the total area) have been mapped recently to modern standards. These are areas that are of interest for one reason or another: for navigation into major ports, for scientific interest where there are strong currents, for engineering purposes prior to offshore construction projects, and so forth.
Remember the recent disappearance of the Malaysian Airlines flight 370, assumed lost off the coast of Australia? They could not really begin looking for it without first getting a decent map of the ocean floor. It was "uncharted" for the purpose of that search - for most people, "really deep" is all you need to know for practical purposes, but in this case the information about the seabed that was needed was not available.
See MH370 Operational Search Update—10 December 2014 for updates on the search (and the "charting" operation that is ongoing in that region).
