How to make player lose health every 2 seconds he is in a trigger?

I'd start a coroutine on OnTriggerEnter and stop it on OnTriggerExit. The coroutine would loop removing health and waiting for 2 seconds. Something like this:

 Coroutine underwaterDamage;
 
 void OnTriggerEnter() {
     underwaterDamage = StartCoroutine(UnderwaterDamage());
 }
 
 void OnTriggerExit() {
     StopCoroutine(underwaterDamage);
 }
 
 IEnumerator UnderwaterDamage() {
     while (true) {
         player.Health -= 10;
         yield return new WaitForSeconds(2f);
     }
 }