Why does an iceberg on have a small amount of it sticking up out of the ocean?
There’s a few reasons for this. The first is water is one of the few substances on earth that is actually less dense as a solid than as a liquid. This is why I’ve floats in your glass as well.
A few other things that make ice bergs more buoyant in general is that they are made of fresh water while the ocean is salt water. This is the same effect that the Uber salty Dead Sea has where the salt increases the density of the water making you extra buoyant.
Third is there is a lot of trapped air in ice bergs as well.
Why there is more above the water than below? That just has to do with the iceberg’s density being close to the surrounding water so it floats low.
You can read some more in depth info here: https://beyondpenguins.ehe.osu.edu/issue/icebergs-and-glaciers/all-about-icebergs