http://buoybay.noaa.gov/

This is a great site for many aspects of physical oceanography, estuarine/marine biology, marine chemistry, tides, winds, and meteorology. It would also have great significance when discussing things like water and air pollution and eutrophication.

You can get high res data on wind, water level, salinity, oxygen, etc etc and work on plotting and/or analyzing graphs. It makes it very easy to see any relationships - like temp and O2, for example.