A sea is a big area of salty water. It is bigger than a lake and smaller than an ocean. Many animals and plants live in the sea.
We swim in the sea in summer.
Fish live in the cold sea water.
This meaning shows the sea close to land or a smaller part of the ocean. It is used when talking about local water areas near the coast.
The sea near our town is very calm.
We saw dolphins in the sea by the beach.
We use 'sea' to talk about many things or lots of something. It does not mean water here but shows a big amount or number.
There is a sea of books in the library.
She has a sea of ideas for the project.
This meaning talks about particular seas with their own names, a part of the ocean that we call by a special name.
The Mediterranean Sea is warm and beautiful.
Many ships cross the Red Sea every day.
When used as a verb (very rare and old-fashioned), 'to sea' means to travel on or across the sea by a boat or ship.
They seaed across the ocean last summer.
Fishermen sea to catch fish early.
Used to describe something large and spread out that looks like a sea, like many people or things moving or covering an area.
A sea of people filled the streets.
We saw a sea of flowers in the fields.
This is a poetic or emotional use of 'sea' to describe strong feelings or emotions that are very large and powerful like a sea.
She was lost in a sea of sadness.
A sea of joy filled his heart today.
