The benefits of the ocean currents at the Great Falls only last up to three or four thousand meters. If you continue down there, the coating will be torn apart by the turbulent currents!
The biggest difference between the ocean in this world and the ocean in Sig's memory, besides the mysterious Seastone Factor, is the difference in the oxygen concentration in the deep sea.
The oceans and deep seas on Earth lack sunlight and plants, resulting in extremely low oxygen concentrations that can only support small organisms. However, in the world's Grand Line, the deep sea is richer in oxygen, making it home to many giant marine mammals and Sea King!
Compared to Sea King, some marine mammals are also enormous in size.
Especially in the deep sea, there are many giant sea monsters, but their intelligence is generally much higher than that of the Sea King —of course, this refers to ordinary Sea King other than the seven mentioned above.
After leaving the Great Falls current, the Red Force was surrounded by many enormous sea monsters, no smaller than ordinary Sea King.
As several officers stood on the ship's sides in different directions, preparing to protect the Red Force, Shanks walked up to the "bull's head" at the bow, casually sat down cross-legged, and even poured himself a bowl of wine from a gourd...
"Gentlemen, we are just passing through, please do us a favor... We beg you!" Shanks said, his Conqueror's Haki fully unleashed, and he downed the wine in his bowl in one gulp before slamming it down on the bow of the ship.
Immediately, the surrounding sea beasts gradually dispersed and disappeared back into the darkness.
Before long, swarms of Sea King gathered there.
In comparison, deep-sea creatures look fiercer and more ferocious, but they don't have the same sense of incongruity as Sea King — Sea King look like ordinary land animals or birds, but have been enlarged to an extreme and have additional organs for survival in the water.
Furthermore, because Sea King are "suitable for survival in the oxygen-rich environment of the deep sea," rather than "only able to survive in the deep sea," their eyesight is generally normal. Unlike the giant sea mammals that can only survive in the deep sea, most of them can only adapt to the pressure of the deep sea and their vision degenerates.
Of course, some marine mammals are able to adapt to multi-level pressure, not only going to shallow waters but also having eyesight that has not deteriorated; however, they are few in number.
In the oxygen-rich environment of the deep sea at a depth of 4,000 meters, there are many giant marine mammals and Sea King. In fact, the density of Sea King alone is no less than that of the Calm Belt.
Of course, the average depth of the ocean is four to five thousand meters. The seawater in other places is not as deep as this. Only the area in the center of the Red Line Continent, where Mary Geoise is located, has a sea depth of ten thousand meters. If the seawater were drained, you would find that this part of the planet is a huge, abrupt basin...
Sig summoned some Sea King to protect them, and the sea monsters stopped harassing them.
The first one looks like Masira, but it has a glowing organ on its head like a lanternfish.
This led the crew to witness many astonishing scenes along the way.
"This is so convenient... With Sig around, we'll never get lost in the ocean, and we can even have Sea King escorting us in the deep sea and the Calm Belt," Lucky Roo remarked from the side.
"Yes, Sig must be the world's number one 'Navigator'!" Gennosuke chimed in from the side.
"No." Sig shook his head, then grinned at his puzzled companions, "Not Navigator, but Seafarer ... hahaha."
When Sig started boasting, Morio and the others laughed and began to mock him.
Sig's "Seafarer" role is progressing very quickly at this point...
In terms of speed of navigation, sailing on the Grand Line is far faster than sailing on the open seas, which convinced Sig that Seafarer must face the unpredictable changes of nature!
Sailing in the Calm Belt allowed for faster ascents than in the Grand Line, which made Sig realize that for Seafarer, reaching the destination is of paramount importance!
From the G6 Branch to the Sabaody Archipelago, the hardships and dangers from nature that they would face along the way were constant; the mission of the "Seafarer" was to arrive safely.
Intentionally choosing a difficult route will not make the role-playing process any easier. Spending several months and enduring various extreme weather conditions is not much different from spending more than a month being pulled by Sea King from the Calm Belt. The latter is more efficient.
From this, Sig can conclude that the key points of his role are: to confront nature, to respect nature, and to control its rage without ever being frivolous.
Diving to a depth of 10,000 meters is, in terms of navigational difficulty, comparable to circumnavigating the first half of the Grand Line, and the progress gained would naturally be enormous...
Moreover, for Sig, the efficiency of navigation is the most crucial factor. In this world, especially on the Grand Line, the least worrisome thing is playing the role of a "Seafarer"!
The goal is to dive to 10,000 meters, but even with the escort of Sea King, it's not as simple as "traveling ten kilometers"; the route still needs to be carefully chosen.
Underwater volcanoes, underwater stone forests, underwater whirlpools... things that should be avoided should still be avoided. Moreover, since Fish-Man Island is located at the only gap beneath the Red Line Continent, theoretically, the Red Line Continent is six or seven thousand meters directly above Fish-Man Island, so a certain angle is required to pass through the gap to reach Fish-Man Island.
After a full day, light could be seen again in the distance.
"We've arrived." Sig saw Fish-Man Island, which he wasn't entirely familiar with, but which left a deep impression on him.
Sig had only been here once, and stayed for only three days, most of which he was unconscious.
The entire Fish-Man Island appears to be inside a giant "bubble," with the lower half of the bubble filled with seawater, while the upper half is inexplicably filled with air.
Although Sig wasn't a true Fish-Man, as a member of the Sun Pirates, he understood that this was the most comfortable environment for Fish-Man —they could move freely in the air and jump into the water at any time.
Even in the underwater structures, the windows and doors are encased in air bubbles; the rooms are ordinary air spaces, while the outside is seawater.
The idea that Fish-Man Race are more "human" than "fish" and that Fish-Man Race should spend all their time in the water, or even live on the seabed, is pure racial prejudice.
Living on Fish-Man Island now is not something the Fish-Man Race chose voluntarily...
On Fish-Man Island, there are also "tree roots" extending from the top. These are the roots of the Eve Tree, which transmit sunlight into Fish-Man Island, making the surrounding area "sunny" even during the day.
Only...
In Sig's few memories of Fish-Man Island, the Sun transmitted from the seabed wasn't very comfortable, far less pleasant than the real Sun.
"How amazing!"
"There are places like this on the seabed...!"
"Is this Fei-ge's and the intern's hometown?"
"I've never been here!" Jack said, feigning annoyance, then added grumbling, "What a cramped place, tch."
Sig had known all along that he was Half Fish-Man had been living outside.
"I've only been here once, and I haven't really explored it properly." Sig shrugged, calculating that he hadn't spent as much time on Fish-Man Island Shanks, who had come with the Roger Pirates!
If you think Sig it carefully, you can deduce that Sig is a slave that Fisher Tiger rescued from Mary Geoise. However, the current Sig, while he doesn't go around bragging about being a slave, doesn't deliberately avoid the topic either.
Many giant sea monsters live around Fish-Man Island, but even the mindless Sea King do not usually attack Fish-Man Island. Instead, they have become part of Fish-Man Island's natural defenses.