Check your map: with the exception a part of South China Sea that is a point of contention with Vietnam, China only has access to shallow water (For instance East China Sea is ~300m deep, which isn't significantly deeper than Norvay's Fjords).

On the contrary the eastern coast of Taiwan has access to very deep sea though.

(This is a well known geostrategic fact, as the small depths of Chinese water are a big weakness for their submarine fleet).