To reach the bottom (of a body of water); to fathom (the depth of body of water or s.o.’s thinking).
Its depth (bottom) cannot be reached.
I (tried to) reach the bottom of that pool but I was unable to reach it.
Someone has reached the bottom of that body of water.
What is in a person’s heart cannot be fathomed.
Tatekkadne tahikin subey bang pikilan a'a ga'i tatekkadne. (Dalilnen: Tatempengnu tahikin subey bang behe a'a ga'i tatempengnu.)
He can fathom the sea but he cannot fathom the thoughts of people. (Its parable: You can block off the sea but the mouth of a person you cannot block off. (Meaning: you cannot stop what he has said.))