Is it too dark to see kids swimming below the surface?
Is this question a joke? Water is clear...you will still see the kids.
No problems seeing the kids at the bottom of our Midnight Blue pool. We actually added Black Onyx to the Midnight Blue Mix to make it even darker which is what we wanted.
Here's a link to our pool.
The color varies widely throughout the day depending on the suns position in the sky. Directly overhead, the pool is a bright blue while at sunset or sunrise, the pool takes a darker blue color.
Hope this helps.
Here is a link that might be useful: Pictures of Midnight Blue