It is my first time using this drone and I took it out to the ocean in Cape Town. I recorded in 24FPS in 4k, using auto settings for the camera with auto colour profile and a blue setting.
The video has come out really horrible and incredibly grainy, could someone help me figuring out why it is like this or am I maybe over reacting and the footage normally is like this?

Here is a link to the video. Most videos I took during this trip are grainy like this.
https://drive.google.com/open?id=1VT48Y9T8XmL4dztV_m66v-VMLU6dQZG8

Here is a Youtube video in 1080p https://www.youtube.com/watch?v=bmcrs6AvjLg

It looks ok, can't see the grain in 1080p on youtube
Have you added to much sharpening in the camera settings

It's very blue , what was the blue setting you used ?

Maybe a UV filter for harsh sun may tone down the blueness

I always use a polarising filter, which gives the image a bit of a boost