Groundwater pollution has become a serious environmental problem.

I saw various aquatic creatures at the aquarium.

This building is equipped with an impermeable wall, preventing water intrusion.

Since he started his new job, he's been lively as if he were a fish back in water.

He absorbs new information like a sponge soaking up water.

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

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

He crossed many mountains and rivers to meet her.

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