Thank you! :)
I didn't use any particular filter. Colors are always lost with depth due to lack of light, underwater photographers use flashes and underwater lights to compensate. And the blue color of the water in the photo appears the deeper, the stronger (as long as there is some light though) and with relatively clean and transparent water. Plus, of course, I do post-processing in Lightroom or Photoshop to bring the photo to a more realistic look, including colors.
It often happens that initially almost the entire picture turns out to be dull green or dull blue, with almost no other colors - this is when there is not enough light. And of course, the color of the water depends on itself - if it is initially yellowish-green or muddy, then to make it blue, it would have to be forcibly shaded when processing the photo, this is a rather inconvenient process.