I think the water floods as much as it can. Once the ground is saturated or if there is a waterproof layer (like clay) it has to puddle (forming puddles up to the size of the seas). If you go on a beach and dig a few meter away from the water, you don't need to dig much (about a foot deep) before your "dry" spot becomes a hole filled with water, so it shows that under sea level, the whole sand bank is saturated. (by the way I like Hyman's fist comment!)

Well, you would normally ask a scientist of sorts about that. To me, I wonder why anyone would think it should. Unfortunately, your question isn't written well. It should be, "Why do you think the water in the oceans doesn't sink into the sand at the bottom?" Avoid too much punctuation such as "?!" because it simply looks silly.

because the bottom's sand rejected the love of ocean's water

I think the main principle is that more dense substance tends to be lower than less dense ones. The density of sand is estimated from 1300 to 2080 kg/m3 meanwhile liquid water is 942.9 to 1050 kg/m3 or so.

No wonder people can't get their head's around the concept of anthropogenic climate change. If this is a serious question, I am going to get quite depressed.