The ocean is the best part of the beach.
Do you like going to the ocean?  All that saline water!
Well I don't drink it. Is it safe to swim in?
Sometimes its not so safe; there are 230 known species in the oceans of the world. Some like sharks are deadly.
How deep is the ocean?
It is different depths in different places  An abyssal plain is an underwater plain on a deep ocean floor at great depth.
What different kind of sharks are there?
Bull sharks are one type.  Another type is tiger sharks.  Of course we all know the great white from Jaws.