Looks like Harry found the wall. Fog... not super surprising. People often talk about memory blocks as "brain fog’ and given the boat and water he found himself within. There were a few ways he could think of on how to remove the fog. Metaphorically creating a light on the boat, navigating into the fog, introducing the concept of sun and light to lift the fog... He just wished he was better at mind magics and knew how to implement any of those ideas in someone else’s mind. He knew the theory for doing it in his own mind but not in another’s. It’s not like he could just cast a lumos and solve the problem. Hoping an idea would come to him, he decided to get Jethro talking.