A few examples of what you can ask Wolfram|Alpha about:
get information about an ocean
compare oceans
Properties of Oceans
look up an ocean property
do computations with ocean properties
Seawater Characteristics
compute properties of the ocean at a given depth
specify temperature and salinity
find the absorption coefficient of seawater
determine the freezing point of seawater
get current tide information
get a tide forecast
get historical tide information