Trouble with swimming in Unity

Hey there. I am working on an FPS with a swimming option. I have it so that I can jump on the surface of the water, then hit a key to dive. After you go underwater everything turns blue, gravity is low, and I can swim freely in all 3 axis. Easy. I also have it when I exit the water level based on the world height, everything is set to normal. My issue lies with the fact that whenever I try and "surface" while still in the water the fog effects for my water flicker on and off and it won't let me go above the surface. I basically want it so that if I swim close to the top, it will send me into surface mode smoothly. Here's my water script.

  var waterLevel : float;
     var isUnderwater: boolean;
     var normalColor: Color;
     var underwaterColor: Color;
     private var chMotor: Player_Controller;
     private var chLook: Mouse_Look;
     private var surface: boolean;
     private var controller: CharacterController;
     private var moveDirection = Vector3.zero;
     
     function Start () 
     {
         chMotor = GetComponent(Player_Controller);
         chLook = GetComponent (Mouse_Look);
         controller = GetComponent(CharacterController);
     
     }
     
     function OnTriggerEnter (other: Collider){
         if (other.gameObject.name == "Surface" && !isUnderwater){
         chMotor.gravity = 0;
         surface = true;
         }
     //I can't get it to work when if(other.gameObject.name == "Surface" && isUnderwater) is the trigger function.
     }
     
     
     function Update () 
     {
      if (surface == true && Input.GetKeyUp (KeyCode.E)){
          isUnderwater = true;
          surface = false;
          
      }
     
     
      if ((transform.position.y < waterLevel) != isUnderwater)
      {
          isUnderwater = transform.position.y < waterLevel;
          if (isUnderwater && !surface) SetUnderwater();
          if (!isUnderwater) SetNormal();
          
      
      }
      
     
     }
     
     function SetNormal()
     {
         RenderSettings.fogColor = normalColor;
         RenderSettings.fogMode = FogMode.Linear;
         RenderSettings.fogStartDistance = 0f;
         RenderSettings.fogEndDistance = 25000f;
         chMotor.gravity = -10000;
         chMotor.speed = 100;
         chMotor.speedStore = 100;
         chMotor.runspeed = 250;
         chLook.Axis = chLook.Axis.MouseX;
     
     }
     
     function SetUnderwater()
     {
         RenderSettings.fogColor = underwaterColor;
         RenderSettings.fogMode = FogMode.Linear;
         RenderSettings.fogStartDistance = 149.26f;
         RenderSettings.fogEndDistance = 1000f;
         
         chMotor.gravity = -1000;
         chMotor.speed = 65;
         chMotor.speedStore = 65;
         chMotor.runspeed = 100;
         chLook.Axis = chLook.Axis.MouseXandY;
     
         
     }