Perlin noise in Unity (from this tutorial https://youtu.be/f6cAAjMfPs8) // modified

wave.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GenerateWaveScript : MonoBehaviour {

    [Range(0.1f, 20.0f)]
    public float heightScale = 5.0f;

    [Range(0.1f, 40.0f)]
    public float detailScale = 5.0f;

    private Mesh myMesh;

    private Vector3[] vertices;

	private void Update()
	{
        GenerateWave();
	}


	void GenerateWave() {
        myMesh = this.GetComponent<MeshFilter>() .mesh;
        vertices = myMesh.vertices;

        int counter = 0;
        int yLevel = 0;

        for (int i = 0; i < 11; i++)
        {
            for (int j = 0; j < 11; j++) {
                CalculationMethod(counter, yLevel);
                counter++;
            }
            yLevel++;
        }

        myMesh.vertices = vertices;
        myMesh.RecalculateBounds();
        myMesh.RecalculateNormals();

        Destroy(gameObject.GetComponent<MeshCollider>());
        MeshCollider collider = gameObject.AddComponent<MeshCollider>();
        collider.sharedMesh = null;
        collider.sharedMesh = myMesh;
    }


    public bool waves = false;
    public float wavesSpeed = 5.0f;
    void CalculationMethod(int i, int j) {
        Vector3 p = this.transform.TransformPoint(vertices[i]);

        if (waves) {
            vertices[i].z = Mathf.PerlinNoise(
                Time.time / wavesSpeed + p.x / detailScale,
                Time.time / wavesSpeed) * heightScale;
                vertices[i].z -= j;
        } else {
            vertices[i].z = Mathf.PerlinNoise(
                p.x / detailScale,
                0) * heightScale;
            vertices[i].z -= j;
        }
    }
}