How came Victoria didn't see Bella when Bella is in the water/drowning..?

Victoria did know that Bella was in the water. She was going to kill her. Fortunately, Jacob got Bella out of the water before Victoria got to her.

She did, But Jake and Sam were coming so she didn't mess with Bella.

i think she did..............but........she new jacob was coming so she did not even attempt to kill her.

she saw

She did see her but also saw Jacob and took off before he saw her.

Well, there's two different answers to that.

In the novel, Victoria was concentrating on the pack and escaping them. So perhaps, while goading through the ocean and passing Bella, due to her focus being mainly on Sam's pack she didn't even notice Bella.

In the movie, she did see Bella and was making a beeline for her. But Jacob and Sam appeared just in time, and Jacob grabbed Bella and pulled her out of the water before Victoria could attack her. If you ever see the movie again, look for the part where Victoria's eyes are sticking out of the surface of the ocean and watching Jacob and Bella on the beach. Then you'd know that she acknowledged Bella's presence. :)