Automated txt reply when phone is turned off

I'm a scuba diver and spend most of my days underwater away from my phone.

I like to turn my phone off when I go diving to save battery.

As a result, I miss many phone calls as a result and nobody likes to leave voicemails anymore.

It would be awesome if I can have my phone automatically text a caller while the phone is off with an automated txt message like, "unfortunately I'm currently scuba diving at the moment and cant get to my phone, pls reply to this text and I'll get back to you as soon as possible."

Is there anyway to do this? I've googled it and found nothing.

Thanks in advance for your help ppl of reddit.