Underwater view

The underwater view is rendered as a full-screen post-processing effect. The view is rendered in one of the following ways:

  • Using a simple analytic formula to estimate light absorption by the water volume.

  • If volumetric fog is enabled, the underwater view is included in the volumetric buffer and rendered using volumetric lighting, supporting light shafts and light shafts from shadows.

Define the underwater area

To change the area where the camera displays an underwater view for a non-infinite water surface, use the Volume Bounds setting. Follow these steps:

  1. Create a GameObject with a collider component, for example a cube with a Box Collider component.
  2. Place the GameObject where you want the underwater view to be visible.
  3. In the collider component, select Edit Collider to set the size of the visible underwater area.
  4. Select the water GameObject.
  5. In the Inspector window, under Appearance, under Underwater, set Volume Bounds to the GameObject you created.

To set the area of the underwater view for an ocean, follow these steps:

  1. Select the ocean GameObject.
  2. In the Inspector window, under Appearance, enable Underwater.
  3. Adjust Volume Depth.

Water line

When the camera is at the limit of the water's surface, the underwater view adds a boundary when transitioning from below to above the water's surface.

A view at the same level of a water surface. A clear boundary separates the fluctuating water surface above and the black below.

To customize the water line even more, you can sample the generated underwater buffer in a Custom Pass by using the HD Sample Buffer node from the Shader Graph using the IsUnderwater option from the Source Buffer dropdown.

Refer to the Waterline scene in the HDRP Water samples for more details.

Limitations

  • When using a custom mesh, underwater doesn't behave as expected if the mesh's Y position isn't at 0, or if the mesh isn't flat.
  • The Receive Fog option on transparent materials also disables underwater. This can be useful to disable absorption on objects when using excluder underwater (like a porthole in the hold of a boat), or as an optimization when you know that fog doesn't affect the object's color.

Additional resources