How to define the selected collider?

Hi guys. I've created a water and I want Box to fall into it and then drift. My script is:

var Box1 : GameObject;
var drift = false;
var speed = -0.5;

function Start(){
    Box1 = GameObject.Find("Box1");
}
//falling into water
function OnTriggerEnter (other : Collider) {
    if(other.gameObject.Find("Box1")){
        Box1.rigidbody.useGravity = false;
        drift = true;
        print(other);
    }
}
//emersion
function OnTriggerExit (other : Collider) {
    if(other.gameObject.Find("Box1")){
        Box1.rigidbody.useGravity = true;
        print("wynurzenie");
    }
}
//drift
function Update(){
    if(drift == true){
        Box1.transform.Translate(0, 0, speed*Time.deltaTime);
    }
}

and works perfectly. But Box starts drifting even if other objects fall into water (the Trigger). How to define that only the box is the chosen collider? Thanks for any answer, this forum is really great :)

There is something called tag that you simply add

if(other.transform.tag == "box1"){
//do something
}

and there is something called name

if(other.transform.name == "box1"){
//do something
}

and you can use layer so there are many ways to do it.