Put the summary of the bug you're having here
when using night vision spell underwater is not transperant
What I expected to happen was...:
I thought that under water everything would be brighter
What actually happened was...:
It was just blue it wasn't a transparent blue.
Steps to Reproduce:
1. Drink potion of night vision
2. ... swim underwater/it was also raining.
3. ... everything will be blue you can see more then 10 blocks in front of you.
Thank you for your report! However, this issue was reported earlier as MCPE-9679. Please add a comment summarizing your experience there. In the future consider doing a search, to check if your issue doesn't exist already.