The water of that river was so hot, if Isiah was functioning with divine energy he would have been boiling at this point, however, he was just battling to stay above the water, nothing more.
Isiah knew how to swim because on earth his parents taught him that he knew a lot of things. After all, they wanted him to be accomplished as their successor.
He was in several classes since he was young, and he learned a lot of skills including swimming.
He was afraid of the hot water which made him tremble a lot before he got his balance back.
" That was so close, i thought that i was going to die, it was so far and hot which made me think only of impossibilities"
Isiah was completely wet, he shook his head for a bit to remove water from his hair that was sticking to his face now, then he remembered the grimoire.
' I think it got destroyed completely , I have to get out to check on it ' He thought .