Some islands in the New World change, or completely hide their magnetic fields, which makes a special New World Log Pose necessary so as not to get lost. Furthermore, the stability of the magnetic field of an island tends to indicate how stable that island is. There are also a few rare islands in the New World that do not get caught by a Log Pose at all.
Other islands of interest within the New World are Wano Country, where the legendary swordsman, Ryuma, as well as Kin'emon and Momonosuke originated from. Also, somewhere in the New World is an island with a special shop where Vivre Cards are manufactured. The Marine Base G-5 also resides here, and according to Aokiji, it is full of problems. As is later demonstrated, the Marines of this base are wild and tend not to follow their orders. Marine Headquarters was also relocated to this sea some time within the two year timeskip and after the Whitebeard War.
According to Gekko Moriah, one will lose everything one cherishes in the New World, something he personally experienced. He also claimed that one shall face what he calls "The Ultimate Nightmare" there, indicating it is a very dangerous place for even the most talented pirates like himself. The New World is such a abhorrent challenge that some pirates refer to the first half of the Grand Line as "paradise" when comparing it to the second half.
While the "Paradise" of the Grand Line possesses highly volatile and unpredictable weather conditions, the "New World" is even more erratic. While certain islands are relatively simple in terms of weather and climate, such as the snowy Yukiryu Island and the rainy island the Kid Pirates were on, other portions of the ocean defy the very laws of physics and nature themselves. Examples include the lightning rain of Raijin Island, the Firetank Pirates being drawn toward a giant black sphere floating in the sky in the middle of the sea, and the On Air Pirates running on air.
The term "New World" is a reference to the Western Hemisphere (including North America, South America, Central America and the Caribbean), which was nicknamed the "New World" during the era of European exploration/colonization. This was in contrast to the "Old World", or the Eastern Hemisphere in the perspective of a eurocentric world view.
In the anime, the New World is entered differently than in the manga. Instead of coming out in a sea of fire, the Straw Hats emerge into a storm, and effectively the Maubeugemour Sea.