Sea content is not updated for more than a year. I hope PA would update it soon.
And in the mean time, we have some ideas to share with you, hope you will take a look.
When sailor explore the island (barter), it'll randomly give quest for a rare sailor.
It can be a quest chain give hints about locations of famous sailor in the old tales.
Rare sailor may buff LT for the ship, decrease parley amount when bartering or randomly fishing.
Fish will go to the inventory of player, like how sailor get the salt water from ocean.