You have your own symbolism so it helps to break down a powerful dream like this.
You have several symbols:
The nice old man
TG - The Elephant
The deep pool
In a notebook describe each symbol and the attributes they had in the dream as well as your personal associations with them. ie. Do you see elephants as wise? Or do you associate them as big things people are in denial about such as 'the elephant in the room'. How does your mind see an elephant?
Then, dialogue with the wise old man and with the elephant.
Start out by writing something like:
Hexed: Elephant, who are you?
Elephant: I am...(Write the first things that come to your mind, stream of consciousness style. Don't think or edit as you do it. Read it back later)
Hexed: (Ask any follow up questions...)
You will be amazed at what can come up when you work with your dreams this way.
It sounds like a really important dream.