Are there any uncharted waters left on earth?
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.