What do we know about the sea Most of us have seen it. We know that it looks very pretty when the sun is lighting on it. We also know that it can be less pretty when the weather is terrible. What other things do we know about it The first thing is that the sea is very big. Look at a map of the world and you’ll find there is less land than sea. The sea covers of the world. The sea is very deep in some places. Some parts of the sea are very shallow. At a place near Japan, the sea is nearly 11 kilometres deep! If the highest mountain in the world were put into the sea at the place, there would be two kilometres of water above it.
The word "it" in the last sentence of this passage means ______ .