I have found a iphone 11 pro max in the same area where I lost my phone on the sea bed near the beach. The phone I found is not my phone an I will like to get it back to the owner. However, I have not found my phone while searching that moment.

If the related article link at the top of this page which says to look for a message saying the phone has been lost and gives you a number to call, then this is also included, which is what you should do:

If you are unable to contact the insurance carrier or return the iPhone, please contact local law enforcement to report that you have found a lost or stolen iPhone.

Apple doesn't get involved in lost or stolen goods, so turning it over to the local authorities is the best option.

And I want you to know it's great you want to do the right thing and get the phone to its rightful owner! Good On You!