I saw various aquatic creatures at the aquarium.

Groundwater pollution has become a serious environmental problem.

Kazumi is my best friend.

I have been to Suishiei.

The European water vole is a small mammal native to Europe.

This steam is what you see when water vapor cools down.

This project is difficult, and the proverb 'highly-skilled men are the first to be exhausted' applies.

He is exactly in the state of 'A frog in a well does not know the vast ocean.'

He crossed many mountains and rivers to meet her.

Please remember this old proverb, 'The friendship of a gentleman is insipid as water.'