Hey kiddo! Have you ever seen the sea at night and it looked like someone spilled a big bucket of milk in it? That's what people call the "milky seas effect"!
So, the milky seas effect happens when the water in the sea lights up at night. This can happen because of tiny little creatures called "bioluminescent plankton" that live in the water. These plankton have a chemical reaction inside their bodies that makes them give off a little bit of light.
Normally, you wouldn't be able to see these tiny plankton because there are so many of them, and they're so small. But when there are A LOT of them in one place, like in a milky sea, it can create a really cool effect, almost like the sea is glowing!
Scientists think that the milky seas effect happens because of something called "bioluminescent bacteria". These are bacteria that live in the water and eat the plankton. When there are enough plankton around, the bacteria start to glow too, which makes the sea look even milkier.
The milky seas effect is really rare, and scientists still don't know exactly why it happens or how often it happens. But it's really cool to see if you ever get the chance!