Jaya is a forest-covered island that was once much larger than it is now, due to over half of it being launched into the White-White Sea by Knock-Up Stream.
The Florian Triangle is the stretch of sea that one has to cross over to reach to the Fishman Island. It is covered in a fog so thick that it blocks out all sunlight.
Sabaody Archipelago is an area close to the Red Line. Though it is called an archipelago, it is actually a massive mangrove forest growing out from middle of the ocean with each tree of the forest serving as an "island" for which people live on.
The Tarai Current is a giant whirlpool that connects the World Government's three major facilities: Enies Lobby, Impel Down and the Marine Headquarters. This current allows World Government and Marine ships to move between the three locations privately.