Kukui hated to admit it, but he loved ships. As anyone would know most ships are made of wood, and the amount of wood needed for a single ship could equate to anywhere from a single tree to a small forest. With this much wood around, it was like Kukui was back in his home island exploring his powers to the fullest. And he LOVED it. 

A little patch to the ship here, a patch there. A support beam needs replacing? Done. Mast is damaged? Repairing now. People boarding the ship? ...

... People boarding the ship? 

Kukui 'swam' to where he felt people enter, a hole in the side that had just opened up,  and observed the two new arrivals. He had recognized the injured coughing man as another who was in the sea stone prison. Another runner just like him and Cera! And the woman seems to be his ally. 

Before Kukui could reveal himself, the woman raced down the halls, leaving the room. Kukui, making sure Gerald had gotten inside, closed the hole in the wall before following Meishu, Kukui still hidden. 

As they moved Kukui noticed how quickly she was moving through the ship and realized that this ship most likely either belonged to her or belonged to her captain. And as they reached the ships controls, Kukui brightened at the confirmation that, yes, this was indeed the woman's ship as she began turning nobs and buttons.

And then suddenly, the boat began to shake. And not ever having been fused to a boat with an engine Kukui could only do one thing.

He shot out of the ground, grabbed the railing and began vomiting into the ocean.