WaterSystem - Part 1

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

public class WaterSystem : MonoBehaviour
{
    public static WaterSystem Instance { get; private set; }
    public float waterLevel = 0f; // Set this in the inspector

    private void Awake()
    {
        if (Instance == null)
        {
            Instance = this;
            DontDestroyOnLoad(gameObject);
        }
        else
        {
            Destroy(gameObject);
        }
    }

    public bool IsUnderwater(Vector3 position)
    {
        return position.y < waterLevel;
    }
}