The ocean was indeed vast and not always calm at all. There were no islands on the way at all. Damian was going 100 kilometers per minute. It wouldn't have taken fifteen minutes before he was there, but he did notice many dungeons on the way. For each one he stopped at, he built a small steel cage to trap a random monster underwater, collecting its ID.
The monsters knew better than to come near him with the level of mana and aura he exuded. He would have to think of something to make an underwater unbreachable place to give access to those dungeons for common people.
He could see the massive island from afar — it was in the all-natural island shape all around except one side, where it was a straight line, as if some half-cut cookie. Land-breaker's work was indeed impressive.
