Unity3D: Underwater Effect

Creating immersive water scenes in Unity3D requires more than just terrain and objects. While the engine excels at building landscapes with first-person cameras, adding skyboxes, directional lighting, and fog effects, something essential is missing: realistic underwater rendering.

When the camera is underwater, there is no visual distinction between submerged and surface views. This limitation is particularly noticeable in water-heavy scenes or games featuring swimming and diving mechanics. The solution involves an underwater effect script to enhance visual immersion.

Implementation

Create a new C# script named Underwater:

using UnityEngine;
using System.Collections;

public class Underwater : MonoBehaviour {

	// Attach this script to main camera
	// And Define variable underwaterLevel up
	// to your water level or sea level Y-coordinate
	public float underwaterLevel = 7;

	// These variable to store
	// The scene default fog settings
	private bool defaultFog = true;
	private Color defaultFogColor;
	private float defaultFogDensity;
	private Material defaultSkybox;
	private float defaultStartDistance;

	void Start () {
		// store default fog setting
		// we need to restore fog setting
		// after we go to surface again
		defaultFog = RenderSettings.fog;
		defaultFogColor = RenderSettings.fogColor;
		defaultFogDensity = RenderSettings.fogDensity;
		defaultSkybox = RenderSettings.skybox;
		defaultStartDistance = RenderSettings.fogStartDistance;

		// set the background color
		camera.backgroundColor = new Color(0, 0.4f, 0.7f, 1);
	}

	void Update () {
		// check if we below the sea or water level
		if (transform.position.y < underwaterLevel) {
			// render new fog with blue color
			// Or you can change the color to
			// match your water
			RenderSettings.fog = true;
			RenderSettings.fogColor = new Color(0, 0.4f, 0.7f, 0.6f);
			RenderSettings.fogDensity = 0.1f;
			RenderSettings.fogStartDistance = 0.0f;

			// add this if you want to add blur effect to your underwater
			// but first add Image Effect (Pro) Package to your project
			// Add component Image Effect > Blur to Main camera
			this.GetComponent<BlurEffect>().enabled = true;
		} else {
			// revert back to default setting
			RenderSettings.fog = defaultFog;
			RenderSettings.fogColor = defaultFogColor;
			RenderSettings.fogDensity = defaultFogDensity;
			RenderSettings.skybox = defaultSkybox;
			RenderSettings.fogStartDistance = defaultStartDistance;

			this.GetComponent<BlurEffect>().enabled = false;
		}
	}
}

Setup Instructions

1. Attach the script to the Main Camera (typically a child object of First Person Controller)
2. Add the Image Effect > Blur Effect component to the main camera
3. Import Image Effect (Pro Only) assets via Assets > Import Package > Image Effect

Important Notes

The blur effect requires Unity3D Pro. For Indie versions, comment out or remove these lines:

// remove or comment this code if you use Unity3d indie version
this.GetComponent<BlurEffect>().enabled = true;
// and this code also
this.GetComponent<BlurEffect>().enabled = false;