1. Water under the bridge
Meaning: Something in the past that cannot be undone but is forgive or accepted
E.g. That argument we had is just water under the bridge now—don't even worry about it.
2. Keep (one’s) head above water
Meaning: To try very hard to survive financially or handle a lot of work
E.g. We all have to co-operate just to keep our heads above water.
3. In hot water
Meaning: In trouble because of something that you have done
E.g. Rick’s temper had landed him in hot water again.
4. Like a fish out of water
Meaning: To feel uncomfortable because you are in an unfamiliar situation
E.g. When Carla transferred to a new school, she was like a fish out of water because she didn't know anyone there.
5. As a duck takes to water
Meaning: Easily and naturally
E.g. My son is very social, so he took to kindergarten as a duck takes to water.
6. Blood is thicker than water
Meaning: People who are related have stronger obligations to each other than to people outside the family.
E.g. My relatives insist that blood is thicker than water, but I just can't blindly condone the bizarre things that some of them do.
7. Spend money like water
Meaning: To spend too much money
E.g. For years he was an absolute penny-pincher. Now that he's got asteady job, he spends money like water.
8. Of the first water
Meaning: Something that is of the first water is of the finest or most exceptional quality (like being compared to a diamond)
E.g. The restaurant is renowned for serving food of the first water.
9. (not) hold water
Meaning: To not be or not appear to be true, verifiable, or able to be supported by facts.
E.g. I'm afraid that excuse just doesn't hold water with me.
10. Water something down
Meaning: To reduce the effectiveness or force of something.
E.g. The new laws watered down the power of the president.
Sea & Ocean Idioms
11. Plenty of (other) fish in the sea
Meaning: Said to someone whose relationship has ended and there are other people in the world to meet and date
E.g. Don't cry over Pierre - there are plenty more fish in the sea!
12. A drop in the ocean
Meaning: A very small amount compared to what is needed
E.g. My letter of protest was just a drop in the ocean.
13. The world is sb’s oyster
Meaning: If the world is your oyster, you can do what you want or go where you want
E.g. You're young and healthy and you have no commitments - the world is your oyster.