You should have used those 4-5 hours to discover each of the islands to the north if you didn't - you get lots of energy for gathering all that knowledge, I think it's something like +30 total

Getting 100% knowledge in this game is one of the hardest things ever, I'm above 90% and it's an insane grind
Grinding mob knowledge grades to S is even more annoying just because it's RNG, it's worth doing at Pirates though