public bool trigger;
public string escenaFinal; //nombre de la escena
public Vector3 coord;

void Start(){

}

void OnTriggerEnter(Collider other) {
    if (other.tag == "Player") {

        trigger = true;    //Trigger true

        }
    }

void OnTriggerExit(Collider other){

    if (other.tag == "Player") { //Sale del trigger falso

        trigger = false;

    }
}

void Update(){

}

void OnGUI(){
    if (trigger) {
        GUI.Box (new Rect (0, 60, 200, 25), "Presiona K"); //Estamos en trigger
        if(Input.GetKeyDown(KeyCode.K)){ //Si está dentro del Trigger y pulsa la letra K
            GameObject.FindGameObjectWithTag("Player").transform.position = coord;
            SceneManager.LoadScene(escenaFinal); //Cargamos la escena
            GameObject.FindGameObjectWithTag("Player").transform.position = coord;
        }
    }
}