The ocean isn't supported by a single crust, but rather by the oceanic crust, which is a type of lithosphere.

Here's a breakdown:

* Lithosphere: This is the rigid outermost layer of the Earth, composed of the crust and the uppermost part of the mantle. It's divided into tectonic plates.

* Oceanic crust: This is the thinner and denser type of crust that forms the ocean floor. It's primarily composed of basalt and gabbro.

So, the ocean sits on top of the oceanic crust, which is part of the larger lithosphere. The tectonic plates move and interact, causing the ocean floor to spread, subduct, and create new crust at mid-ocean ridges.