EnterBoat Script

public class EnterBoat : MonoBehaviour
{
    [Header("In-Boat Positions")]
    public float xValue, yValue, zValue;

    [Header("Exit-Boat Positions")]
    public float Xvalue, Yvalue, Zvalue;

    private bool inBoat = false;
    BoatDrive vehicleScript;
    public GameObject Node;
    public GameObject player;
    public GameObject cameraBoat;

    void Start()
    {
        player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonUserControl>().enabled = true;
        player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter>().enabled = true;
        vehicleScript = GetComponent<BoatDrive>(); // You want to make sure that the vehicleScript equals the CarUserControl Script of our car.
        player = GameObject.FindWithTag("Player"); // We want to make sure our player is in the scene, otherwise this script won't work.
        vehicleScript.enabled = false; // Once our vehicleScript has been found, we want to disable it for now, as we enable it later on.
        cameraBoat.SetActive(false); // We want to disable the car camera and use our player camera.
        // guiObj.SetActive(false); Text with "Press E" for example
    }

    void OnTriggerStay(Collider other) // When being into the ColliderBox with Trigger Checked
    {
        if (other.gameObject.tag == "Player" && inBoat == false)
        {
            if (Input.GetKey(KeyCode.H))
            {
                player.GetComponent<Rigidbody>().constraints = RigidbodyConstraints.FreezePositionX | RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionZ;
                player.GetComponent<Rigidbody>().freezeRotation = true;
                player.GetComponent<Rigidbody>().isKinematic = true;
                player.GetComponent<Animator>().enabled = false;
                player.GetComponent<Animator>().Play("Idle");
                player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonUserControl>().enabled = false;
                player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter>().enabled = false;
                player.transform.parent = Node.transform; // We have set the player as a parent of the Car. We here switch to the Car.
                player.transform.localPosition = new Vector3(xValue, yValue, zValue); // We are setting the players position to the assigned values for x, y, z
                vehicleScript.enabled = true; // We want to enable our vehicleScript here, so we can drive.
                player.SetActive(true); // We want to disable our player, so we can switch to the car. Otherwise we will see the player while we drive.
                inBoat = true; // We want to say that we are in the car.
                cameraBoat.SetActive(true); // We want to change the current camera to the car camera.
            }
        }
    }

    void Update()
    {
        if (inBoat == true && Input.GetKey(KeyCode.X)) // If we are in the car and we press "X", we want to get out of the car and set everything back.
        {
            player.transform.localPosition = new Vector3(Xvalue, Yvalue, Zvalue);
            player.GetComponent<Rigidbody>().constraints = RigidbodyConstraints.None;
            player.GetComponent<Rigidbody>().freezeRotation = true;
            player.GetComponent<Rigidbody>().isKinematic = false;
            vehicleScript.enabled = false;
            player.SetActive(true);
            player.GetComponent<Animator>().enabled = true;
            player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonUserControl>().enabled = true;
            player.GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter>().enabled = true;
            player.transform.parent = null;
            inBoat = false;
            cameraBoat.SetActive(false);
        }
    }
}