Since absorbing the Nautilus' Compass, his visions of the future had become stronger, clearer, and more precise. Hence, he had realized it was time to leave the pirate island and a big problem was chasing them.
The Sea Serpent!
Just as they had expected, news of the Nautilus' Compass had spread through the depths of the Violent Sea and the still-living Sea Serpent had begun its pursuit of them.
The entire crew had been nervously traveling since the day they left the pirate island of Walkas' group, having escaped, in Minos' words, for a matter of just a few hours!